ASTM D4741-21

Standard Test Method for Measuring Viscosity at High Temperature and High Shear Rate by Tapered-Plug Viscometer

SIGNIFICANCE AND USE
5.1 Viscosity measured under the conditions of this test method is considered to be representative of that at the temperatures and shear rates but not the pressures in the journal bearings of internal combustion engines under operating conditions.  
5.2 The relevance of these conditions to the measurement of engine-oil viscosity has been discussed in many publications.6  
5.3 The high temperature high shear (HTHS) viscosity at this shear rate can be measured at other temperatures using this apparatus. This is achieved by the use of a different range of Newtonian calibration fluids. The precision has not been studied for any temperature or viscosity range not noted in the precision section.
SCOPE
1.1 This test method2 covers the laboratory determination of the viscosity of oils at 150 °C and 1 × 106 s–1 and at 100 °C and 1 × 106 s–1, using high shear rate tapered-plug viscometer models BE/C or BS/C.  
1.2 Newtonian calibration oils are used to adjust the working gap and for calibration of the apparatus. These calibration oils cover a range from approximately 1.4 mPa·s to 5.9 mPa·s (cP) at 150 °C and 4.2 mPa·s to 18.9 mPa·s (cP) at 100 °C. This test method should not be used for extrapolation to higher viscosities than those of the Newtonian calibration oils used for calibration of the apparatus. If it is so used, the precision statement will no longer apply. The precision has only been determined for the viscosity range 1.48 mPa·s to 5.07 mPa·s at 150 °C and from 4.9 mPa·s to 11.8 mPa·s at 100 °C for the materials listed in the precision section.  
1.3 A non-Newtonian reference oil is used to check that the working conditions are correct. The exact viscosity appropriate to each batch of this oil is established by testing on a number of instruments in different laboratories. The agreed value for this reference oil may be obtained from the chairman of the Coordinating European Council (CEC) Surveillance Group for CEC L-36-90, or from the distributor.  
1.4 Applicability to products other than engine oils has not been determined in preparing this test method.  
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard except those noted below.  
1.5.1 Exception—This test method uses the SI unit millipascal-second (mPa·s) as the unit of viscosity. (1 cP = 1 mPa·s.)  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Dec-2020
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.07 - Flow Properties

Relations

• Refers: ASTM D6708-24 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Mar-2024
• Refers: ASTM D6300-24 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Mar-2024
• Refers: ASTM D6300-23a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Dec-2023
• Refers: ASTM D4683-20 - Standard Test Method for Measuring Viscosity of New and Used Engine Oils at High Shear Rate and High Temperature by Tapered Bearing Simulator Viscometer at 150 °C
• Effective Date: 01-Jun-2020
• Refers: ASTM D5481-13(2020) - Standard Test Method for Measuring Apparent Viscosity at High-Temperature and High-Shear Rate by Multicell Capillary Viscometer
• Effective Date: 01-May-2020
• Refers: ASTM D6300-19a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Dec-2019
• Refers: ASTM D6708-19 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-May-2019
• Refers: ASTM D6708-18 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Apr-2018
• Refers: ASTM D6300-16 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Apr-2016
• Refers: ASTM D6708-16a - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Apr-2016
• Refers: ASTM D6708-16 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Jan-2016
• Refers: ASTM D6708-15 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Jul-2015
• Refers: ASTM D6300-15 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2015
• Refers: ASTM D6300-14ae1 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2014
• Refers: ASTM D6300-14a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2014

Overview

ASTM D4741-21 is a standard test method developed by ASTM International for measuring the viscosity of oils at high temperatures and high shear rates using a tapered-plug viscometer. Specifically, this method determines viscosity at 150°C and 1 × 10⁶ s^–1 as well as at 100°C and 1 × 10⁶ s^–1. The standard is particularly significant for engine oils, as it simulates the conditions present in the journal bearings of internal combustion engines during operation, offering a reliable approach for high temperature high shear (HTHS) viscosity measurement.

This method utilizes Newtonian calibration oils to ensure precise calibration and employs a non-Newtonian reference oil to verify correct operation. The values reported conform to the SI unit millipascal-second (mPa·s).

Key Topics

• High Temperature High Shear (HTHS) Viscosity: Provides representative measurements of oil viscosity under demanding engine conditions.
• Tapered-Plug Viscometer Method: Uses a precisely engineered viscometer to simulate operational shear rates and accurately measure lubricant flow resistance.
• Calibration and Reference Materials: Relies on standardized Newtonian calibration oils (for reliable results across a defined viscosity range) and non-Newtonian reference oils (to check the proper functioning of the apparatus).
• Applicability: Primary focus is on engine oils; the method's relevance to other products has not been established.
• Precision and Repeatability: The method outlines validated precision data within defined viscosity ranges for both temperatures, based on interlaboratory studies.

Applications

ASTM D4741-21 is widely used in the automotive and lubricants industries to assess the operational suitability of engine oils by evaluating their viscosity under high temperature and shear conditions, which closely reflect real engine environments. Key practical applications include:

• Engine Oil Formulation and Quality Control: Ensures that lubricants will maintain protective viscosity in high stress engine locations such as journal bearings.
• Research and Development: Helps lubricant formulators evaluate new base stocks and additive packages for high performance under severe engine conditions.
• Used Oil Analysis: Although primarily intended for new oils, this test can also help assess viscosity changes in used oils, provided proper sample preparation and filtration.
• Standardized Product Comparison: Supports direct comparison among oils by utilizing a rigorously defined, reproducible test environment.

Related Standards

ASTM D4741-21 is part of a broader family of engine oil and viscosity test standards that support quality and performance benchmarking in lubricants:

• ASTM D4683: Test Method for Measuring Viscosity of New and Used Engine Oils at High Shear Rate and High Temperature by Tapered Bearing Simulator Viscometer at 150°C.
• ASTM D5481: Test Method for Measuring Apparent Viscosity at High-Temperature and High-Shear Rate by Multicell Capillary Viscometer.
• ASTM D6300: Practice for Determination of Precision and Bias Data in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants.
• ASTM D6708: Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property.
• CEC L-36-90: European method for the measurement of lubricant dynamic viscosity under high shear conditions.
• IP 370: Measurement standard for lubricant dynamic viscosity under high shear using the Ravenfield viscometer.

Practical Value

Implementing ASTM D4741-21 ensures laboratories, oil manufacturers, and engine developers can consistently evaluate and compare the high temperature high shear viscosity of engine oils. Adherence to this recognized standard promotes product reliability, enhances engine performance, and supports regulatory compliance within the automotive and lubricants sectors.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4741 − 21
Standard Test Method for
Measuring Viscosity at High Temperature and High Shear
Rate by Tapered-Plug Viscometer
This standard is issued under the fixed designation D4741; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* 1.6 This standard does not purport to address all of the
2 safety concerns, if any, associated with its use. It is the
1.1 Thistestmethod coversthelaboratorydeterminationof
6 –1 responsibility of the user of this standard to establish appro-
theviscosityofoilsat150°Cand1×10 s andat100°Cand
6 –1 priate safety, health, and environmental practices and deter-
1×10 s , using high shear rate tapered-plug viscometer
mine the applicability of regulatory limitations prior to use.
models BE/C or BS/C.
1.7 This international standard was developed in accor-
1.2 Newtonian calibration oils are used to adjust the work-
dance with internationally recognized principles on standard-
ing gap and for calibration of the apparatus. These calibration
ization established in the Decision on Principles for the
oils cover a range from approximately 1.4mPa·s to 5.9 mPa·s
Development of International Standards, Guides and Recom-
(cP)at150°Cand4.2mPa·sto18.9mPa·s(cP)at100°C.This
mendations issued by the World Trade Organization Technical
test method should not be used for extrapolation to higher
Barriers to Trade (TBT) Committee.
viscositiesthanthoseoftheNewtoniancalibrationoilsusedfor
calibration of the apparatus. If it is so used, the precision 2. Referenced Documents
statement will no longer apply. The precision has only been
2.1 ASTM Standards:
determined for the viscosity range 1.48mPa·s to 5.07 mPa·s at
D4683Test Method for Measuring Viscosity of New and
150 °C and from 4.9mPa·s to 11.8 mPa·s at 100°C for the
Used Engine Oils at High Shear Rate and High Tempera-
materials listed in the precision section.
ture by Tapered Bearing Simulator Viscometer at 150°C
1.3 Anon-Newtonian reference oil is used to check that the D5481Test Method for Measuring Apparent Viscosity at
workingconditionsarecorrect.Theexactviscosityappropriate High-TemperatureandHigh-ShearRatebyMulticellCap-
to each batch of this oil is established by testing on a number illary Viscometer
of instruments in different laboratories. The agreed value for D6300Practice for Determination of Precision and Bias
this reference oil may be obtained from the chairman of the Data for Use in Test Methods for Petroleum Products,
Coordinating European Council (CEC) Surveillance Group for Liquid Fuels, and Lubricants
CEC L-36-90, or from the distributor. D6708Practice for StatisticalAssessment and Improvement
of Expected Agreement Between Two Test Methods that
1.4 Applicability to products other than engine oils has not
Purport to Measure the Same Property of a Material
been determined in preparing this test method.
2.2 Coordinating European Council (CEC) Standard:
1.5 The values stated in SI units are to be regarded as
CEC L-36-90The Measurement of Lubricant Dynamic Vis-
standard. No other units of measurement are included in this
cosity under Conditions of High Shear (Ravenfield)
standard except those noted below.
1.5.1 Exception—This test method uses the SI unit
millipascal-second (mPa·s) as the unit of viscosity. (1cP =
1mPa·s.)
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.07 on Flow Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 1, 2021. Published January 2021. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1987. Last previous edition approved in 2020 as D4741–20a. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4741-21. the ASTM website.
2 4
This test method is technically identical to that described in CEC L-36-90 Available from Coordinating European Council (CEC), Services provided by
(under the jurisdiction of the CEC Engine Lubricants Technical Committee) and in Kellen Europe, Avenue Jules Bordet 142 - 1140, Brussels, Belgium, http://
IP370. www.cectests.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4741 − 21
2.3 Energy Institute: 5. Significance and Use
IP 370Test Method for the Measurement of Lubricant
5.1 Viscosity measured under the conditions of this test
DynamicViscosityUnderConditionsofHighShearUsing
method is considered to be representative of that at the
the Ravenfield Viscometer
temperaturesandshearratesbutnotthepressuresinthejournal
bearings of internal combustion engines under operating con-
3. Terminology
ditions.
3.1 Definitions:
3.1.1 apparent viscosity, n—viscosity of a non-Newtonian 5.2 Therelevanceoftheseconditionstothemeasurementof
engine-oil viscosity has been discussed in many publications.
liquid determined by this test method at a particular shear rate
and shear stress.
5.3 The high temperature high shear (HTHS) viscosity at
3.1.2 density, n—mass per unit volume.
thisshearratecanbemeasuredatothertemperaturesusingthis
3.1.3 kinematic viscosity, n—the ratio of the dynamic vis- apparatus. This is achieved by the use of a different range of
cosity (η) to the density (ρ) of a liquid at a given temperature. Newtonian calibration fluids. The precision has not been
3.1.3.1 Discussion—In SI, the unit of kinematic viscosity is
studied for any temperature or viscosity range not noted in the
the metre squared per second, often conveniently expressed as
precision section.
millimetre squared per second and termed the centiStoke.
6. Apparatus
3.1.4 Newtonian oil, n—an oil or fluid that at a given
temperature exhibits a constant viscosity at all shear rates or
6.1 Tapered-Plug High Shear Rate Viscometer,ModelBE/C
shear stresses.
(single speed) or BS/C (multi-speed). The viscometer uses a
3.1.5 non-Newtonian oil, n—an oil or fluid that at a given
rotating tapered plug in a matched stator.
temperatureexhibitsaviscositythatvarieswithchangingshear
NOTE 1—Model BE/C has a restricted torque range and may not be
stress or shear rate.
capable of measuring higher viscosities at 100°C.
3.1.6 shear rate, n—velocity gradient perpendicular to the
6.2 Vacuum Extract Pipe, to ensure constant oil level. The
direction of flow.
extract pipe is supplied with all current models.
3.1.7 shear stress, n—theforceperunitareainthedirection
of the flow.
6.3 Calibration Weight (supplied with instrument).
3.1.8 viscosity, n—the ratio between the applied shear stress
6.4 Thermostatically Controlled Heating Bath, with fluid
and rate of shear which is sometimes called the coefficient of
circulator. For acceptable temperature control and recovery
dynamic viscosity and is a measure of the resistance to flow of
time, the temperature difference between the bath and mea-
the liquid.
surement head should be targeted at 4°C and shall not exceed
3.1.8.1 Discussion—It is sometimes called dynamic or ab-
8°C. This temperature difference is influenced by the nature
solute viscosity (in contrast to kinematic viscosity, see 3.1.3).
and rate of flow of the circulating fluid; the length and bore of
3.2 Definitions of Terms Specific to This Standard:
the heating pipes; and the viscosity of the bath fluid.
3.2.1 calibration oils, n—Newtonian oils used to establish
NOTE2—Bathoilwithkinematicviscositynotgreaterthan10mm /sat
the reference framework of viscosity versus torque in this
150°C is recommended.
instrument from which the test oil viscosity is determined.
6.5 Ameans of measuring temperature is not necessary for
3.2.2 non-Newtonian check oil, n—non-Newtonian oil used
currentinstrumentssinceaprecisiontemperaturesensorisnow
to check that the gap or distance between the rotor and stator
6 −1
built-in. For older instruments still in the field, a device with a
will produce the desired operating shear rate of1×10 s .
precision not worse than 60.20°C is necessary.
3.2.2.1 Discussion—Check oil is an acceptable name for
non-Newtonian reference oil.
6.6 The use of an ultrasonic cleaner is recommended.
3.2.3 test oil, n—any oil for which apparent viscosity is to
6.7 The manufacturer offers a package incorporating all the
be determined.
above and including the necessary calibration oils, reference
oils, and bath oil.
4. Summary of Test Method
4.1 The lubricant under test fills the annulus between a 6.8 Vacuum Pump, with suitable liquid trap.
close-fitting rotor and stator.The rotor and stator have a slight,
matching taper to allow adjustment of the gap and hence the
shearrate.Therotorisspunataknownspeed,andthelubricant
For a comprehensive review, see “The Relationship Between High-
viscosity is determined from measurements of the reaction
Temperature Oil Rheology and Engine Operation,”ASTM Data Series Publication
torque by reference to a curve prepared using Newtonian 62 (out of print).
The sole source of supply of the apparatus known to the committee at this time
calibration oils.
is Cannon Instrument Co., State College, PA 16803, http://
www.cannoninstrument.com. If you are aware of alternative suppliers, please
provide this information toASTM International Headquarters.Your comments will
5 1
Available from Energy Institute, 61 New Cavendish St., London, W1G 7AR, receive careful consideration at a meeting of the responsible technical committee,
U.K., http://www.energyinst.org. which you may attend.
D4741 − 21
7. Materials 9.4 Whensettinguptheapparatus,atorquecalibrationshall
8 be performed following the instructions in the manufacturer’s
7.1 Newtonian Calibration Oils —CEC Reference Oils RL
manual.
102, RL 103, RL 104, RL 105, RL 106, and RL 107. Cannon
CertifiedViscosity Reference Standard HT22 (nominal viscos-
9.5 The instrument is supplied by the manufacturer with all
ity of 1.5 mPa·s at 150 °C).
other functions already calibrated and set up. It is recom-
mended that these other initial settings be accepted until
7.2 Non-Newtonian Reference Oil —CECReferenceOilRL
sufficient familiarity is obtained with the use of the apparatus.
232.
When it is desired to modify the initial settings, full instruc-
7.3 Flushing Solvent—White mineral spirit or Stoddard
tions will be found in the manufacturer’s manual.
solvent.
9.6 Itisadvisabletogainaccesstothelistofcalibrationoils
held in the memory of the instrument in order to be familiar
8. Sampling
with its contents and to check that it is in accordance with the
8.1 Testoilsthatarevisuallyfreefromhazeandparticulates
standards actually supplied.
neednotbefilteredbeforeevaluation.Asampleshallbefreeof
9.7 Preparation of Apparatus on All Other Occasions:
particles larger than 3µm. If heavy concentration of smaller
9.7.1 Flush out the measurement chamber using flushing
particles is still visible after filtration through a filter of pore
size 3µm, it is recommended to reduce their concentration by solvent
further filtration. This will reduce the possibility of the par- 9.7.2 Turn on the heating bath.
ticles wedging in the measurement gap and so causing erosion
9.7.3 Refill the measurement chamber with Non-Newtonian
of the rotor/stator or erroneous readings. Do not filter formu-
Reference Oil RL 232.
lated oils through pore sizes below 1 µm because certain
9.7.4 Leavefornotlessthanhalfanhourfortemperatureto
lubricant additives may be removed.
stabilise.
9.7.4.1 Ifthebathdoesnotreachcorrecttemperatureinthis
8.2 Used oils may also be tested in these instruments,
time, then either extend this period or, preferably, address the
though no precision statement is available for these materials.
problem of why heating is slow.
8.2.1 Filter used oils through a suitable filter such as
Whatman GF/C fibreglass filter. The process of filtration is
10. Procedure
greatly accelerated by either warming or applying pressure.
Procedures shall be such that all risk of particulate contamina-
10.1 Outline of Method:
tion is avoided.
10.1.1 The lubricant under test fills the annulus between a
NOTE3—Suggestionshavebeenmadethattheprocessoffiltrationmay close-fitting rotor and stator. The rotor and stator have a
itself cause a change of viscosity by the removal of particles. No doubt if
gradual matching taper to allow adjustment of the gap and
thereisaveryheavyconcentrationofparticlesgreaterthan3µm,thiswill
hence the shear rate. Spin the rotor at a known speed and
be so. It is not expected or intended that this test method will be used for
determine the lubricant viscosity from measurements of the
such oils. Evidence to date is that filtration of used oils from normal
reaction torque by reference to a line prepared using Newto-
enginesinnormalperiodsofuseisacceptable.Itis,however,advisableto
use pressure filtration rather than vacuum filtration so that volatile nian calibration oils.
components will not be removed. No precision statement is available for
10.1.2 Use Newtonian calibration oils (7.1) to adjust the
used oils.
working gap and for calibration of the apparatus. These
calibration oils cover a range from approximately 1.5mPa·s to
9. Initial Preparation of Apparatus
5.9 mPa·s (cP) at 150°C and 4.2mPa·s to 18.9 mPa·s (cP) at
9.1 These instructions relate to instruments incorporating a
100 °C. The test method should not be used for extrapolation
computer, in other words, Models BE/C and BS/C. Changes
to higher or lower viscosities than those of the Newtonian
from earlier editions of this test method are those given in
calibration oils used for calibration of the apparatus (see 1.1).
10.1.5, 10.5.1, 10.5.2, 11.1.2, and 11.1.3 and the use of a
NOTE 5—When operat
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4741 − 20a D4741 − 21
Standard Test Method for
Measuring Viscosity at High Temperature and High Shear
Rate by Tapered-Plug Viscometer
This standard is issued under the fixed designation D4741; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
2 6 –1
1.1 This test method covers the laboratory determination of the viscosity of oils at 150 °C and 1 × 10 s and at 100 °C and 1
6 –1
× 10 s , using high shear rate tapered-plug viscometer models BE/C or BS/C.
1.2 Newtonian calibration oils are used to adjust the working gap and for calibration of the apparatus. These calibration oils cover
a range from approximately 1.4 mPa·s to 5.9 mPa·s (cP) at 150 °C and 4.2 mPa·s to 18.9 mPa·s (cP) at 100 °C. This test method
should not be used for extrapolation to higher viscosities than those of the Newtonian calibration oils used for calibration of the
apparatus. If it is so used, the precision statement will no longer apply. The precision has only been determined for the viscosity
range 1.48 mPa·s to 5.07 mPa·s at 150 °C and from 4.9 mPa·s to 11.8 mPa·s at 100 °C for the materials listed in the precision
section.
1.3 A non-Newtonian reference oil is used to check that the working conditions are correct. The exact viscosity appropriate to each
batch of this oil is established by testing on a number of instruments in different laboratories. The agreed value for this reference
oil may be obtained from the chairman of the Coordinating European Council (CEC) Surveillance Group for CEC L-36-90, or from
the distributor.
1.4 Applicability to products other than engine oils has not been determined in preparing this test method.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard except
those noted below.
1.5.1 Exception—This test method uses the SI unit millipascal-second (mPa·s) as the unit of viscosity. (1 cP = 1 mPa·s.)1 mPa·s.)
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.07 on Flow Properties.
Current edition approved Sept. 1, 2020Jan. 1, 2021. Published October 2020January 2021. Originally approved in 1987. Last previous edition approved in 2020 as
D4741 – 20.D4741 – 20a. DOI: 10.1520/D4741-20A.10.1520/D4741-21.
This test method is technically identical to that described in CEC L-36-90 (under the jurisdiction of the CEC Engine Lubricants Technical Committee) and in IP 370.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4741 − 21
2. Referenced Documents
2.1 ASTM Standards:
D4683 Test Method for Measuring Viscosity of New and Used Engine Oils at High Shear Rate and High Temperature by Tapered
Bearing Simulator Viscometer at 150 °C
D5481 Test Method for Measuring Apparent Viscosity at High-Temperature and High-Shear Rate by Multicell Capillary
Viscometer
D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and
Lubricants
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport
to Measure the Same Property of a Material
2.2 Coordinating European Council (CEC) Standard:
CEC L-36-90 The Measurement of Lubricant Dynamic Viscosity under Conditions of High Shear (Ravenfield)
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from Coordinating European Council (CEC), Services provided by Kellen Europe, Avenue Jules Bordet 142 - 1140, Brussels, Belgium, http://www.cectests.org.
D4741 − 21
2.3 Energy Institute:
IP 370 Test Method for the Measurement of Lubricant Dynamic Viscosity Under Conditions of High Shear Using the Ravenfield
Viscometer
3. Terminology
3.1 Definitions:
3.1.1 apparent viscosity, n—viscosity of a non-Newtonian liquid determined by this test method at a particular shear rate and shear
stress.
3.1.2 density, n—mass per unit volume at a specified temperature. volume.
3.1.2.1 Discussion—
For common fuel and lubricant applications, density at atmospheric pressure is assumed. However, high pressure can impact
density.
3.1.3 kinematic viscosity, n—the ratio of the dynamic viscosity (η) to the density (ρ) of a liquid at a given temperature.
3.1.3.1 Discussion—
In SI, the unit of kinematic viscosity is the metre squared per second, often conveniently expressed as millimetre squared per
second and termed the centiStoke.
3.1.4 Newtonian oil, n—an oil or fluid that at a given temperature exhibits a constant viscosity at all shear rates or shear stresses.
3.1.5 non-Newtonian oil, n—an oil or fluid that at a given temperature exhibits a viscosity that varies with changing shear stress
or shear rate.
3.1.6 shear rate, n—velocity gradient perpendicular to the direction of flow.
3.1.7 shear stress, n—the force per unit area in the direction of the flow.
3.1.8 viscosity, n—the ratio between the applied shear stress and rate of shear which is sometimes called the coefficient of dynamic
viscosity and is a measure of the resistance to flow of the liquid.
3.1.8.1 Discussion—
It is sometimes called dynamic or absolute viscosity (in contrast to kinematic viscosity, see 3.1.3).
3.2 Definitions of Terms Specific to This Standard:
3.2.1 calibration oils, n—Newtonian oils used to establish the reference framework of viscosity versus torque in this instrument
from which the test oil viscosity is determined.
3.2.2 non-Newtonian check oil, n—non-Newtonian oil used to check that the gap or distance between the rotor and stator will
6 −1
produce the desired operating shear rate of 1 × 10 s .
3.2.2.1 Discussion—
Check oil is an acceptable name for non-Newtonian reference oil.
3.2.3 test oil, n—any oil for which apparent viscosity is to be determined.
4. Summary of Test Method
4.1 The lubricant under test fills the annulus between a close-fitting rotor and stator. The rotor and stator have a slight, matching
taper to allow adjustment of the gap and hence the shear rate. The rotor is spun at a known speed, and the lubricant viscosity is
determined from measurements of the reaction torque by reference to a curve prepared using Newtonian calibration oils.
Available from Energy Institute, 61 New Cavendish St., London, W1G 7AR, U.K., http://www.energyinst.org.
D4741 − 21
5. Significance and Use
5.1 Viscosity measured under the conditions of this test method is considered to be representative of that at the temperatures and
shear rates but not the pressures in the journal bearings of internal combustion engines under operating conditions.
5.2 The relevance of these conditions to the measurement of engine-oil viscosity has been discussed in many publications.
5.3 The high temperature high shear (HTHS) viscosity at this shear rate can be measured at other temperatures using this
apparatus. This is achieved by the use of a different range of Newtonian calibration fluids. The precision has not been studied for
any temperature or viscosity range not noted in the precision section.
6. Apparatus
6.1 Tapered-Plug High Shear Rate Viscometer, Model BE/C (single speed) or BS/C (multi-speed). The viscometer uses a rotating
tapered plug in a matched stator.
NOTE 1—Model BE/C has a restricted torque range and may not be capable of measuring higher viscosities at 100 °C.
6.2 Vacuum Extract Pipe, to ensure constant oil level. The extract pipe is supplied with all current models.
6.3 Calibration Weight (supplied with instrument).
6.4 Thermostatically Controlled Heating Bath, with fluid circulator. For acceptable temperature control and recovery time, the
temperature difference between the bath and measurement head should be targeted at 4 °C and shall not exceed 8 °C. This
temperature difference is influenced by the nature and rate of flow of the circulating fluid; the length and bore of the heating pipes;
and the viscosity of the bath fluid.
NOTE 2—Bath oil with kinematic viscosity not greater than 10 mm /s at 150 °C is recommended.
6.5 A means of measuring temperature is not necessary for current instruments since a precision temperature sensor is now
built-in. For older instruments still in the field, a device with a precision not worse than 60.20 °C is necessary.
6.6 The use of an ultrasonic cleaner is recommended.
6.7 The manufacturer offers a package incorporating all the above and including the necessary calibration oils, reference oils, and
bath oil.
6.8 Vacuum Pump, with suitable liquid trap.
7. Materials
7.1 Newtonian Calibration Oils —CEC Reference Oils RL 102, RL 103, RL 104, RL 105, RL 106, and RL 107. Cannon Certified
Viscosity Reference Standard HT22 (nominal viscosity of 1.5 mPa·s at 150 °C).
7.2 Non-Newtonian Reference Oil —CEC Reference Oil RL 232.
7.3 Flushing Solvent—White mineral spirit or Stoddard solvent.
For a comprehensive review, see “The Relationship Between High-Temperature Oil Rheology and Engine Operation,” ASTM Data Series Publication 62 (out of print).
The sole source of supply of the apparatus known to the committee at this time is Cannon Instrument Co., State College, PA 16803, http://www.cannoninstrument.com.
If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting
of the responsible technical committee, which you may attend.
Under the jurisdiction of CEC Engine Lubricants Technical Committee. Cannon Instrument Co. are distributors.
D4741 − 21
8. Sampling
8.1 Test oils that are visually free from haze and particulates need not be filtered before evaluation. A sample shall be free of
particles larger than 3 μm. If heavy concentration of smaller particles is still visible after filtration through a filter of pore size 3 μm,
it is recommended to reduce their concentration by further filtration. This will reduce the possibility of the particles wedging in
the measurement gap and so causing erosion of the rotor/stator or erroneous readings. Do not filter formulated oils through pore
sizes below 1 μm because certain lubricant additives may be removed.
8.2 Used oils may also be tested in these instruments, though no precision statement is available for these materials.
8.2.1 Filter used oils through a suitable filter such as Whatman GF/C fibreglass filter. The process of filtration is greatly accelerated
by either warming or applying pressure. Procedures shall be such that all risk of particulate contamination is avoided.
NOTE 3—Suggestions have been made that the process of filtration may itself cause a change of viscosity by the removal of particles. No doubt if there
is a very heavy concentration of particles greater than 3 μm, this will be so. It is not expected or intended that this test method will be used for such oils.
Evidence to date is that filtration of used oils from normal engines in normal periods of use is acceptable. It is, however, advisable to use pressure filtration
rather than vacuum filtration so that volatile components will not be removed. No precision statement is available for used oils.
9. Initial Preparation of Apparatus
9.1 These instructions relate to instruments incorporating a computer, in other words, Models BE/C and BS/C. Changes from
earlier editions of this test method are those given in 10.1.5, 10.5.1, 10.5.2, 11.1.2, and 11.1.3 and the use of a vacuum extract pipe
to ensure constant oil level (see 6.2).
9.2 Set up the apparatus in accordance with the manufacturer’s manual. Attach the funnel to the side arm, using the rubber sleeve
provided.
NOTE 4—The funnel has a larger bore than stock funnels in order to increase the rate of flow of oil samples.
9.3 It is recommended that the instrument is NOT mounted in a fume cupboard since this draws in dirt particles. Local extraction
over the heating bath is all that is necessary since the manufacturer’s bath is practically sealed.
9.4 When setting up the apparatus, a torque calibration shall be performed following the instructions in the manufacturer’s manual.
9.5 The instrument is supplied by the manufacturer with all other functions already calibrated and set up. It is recommended that
these other initial settings be accepted until sufficient familiarity is obtained with the use of the apparatus. When it is desired to
modify the initial settings, full instructions will be found in the manufacturer’s manual.
9.6 It is advisable to gain access to the list of calibration oils held in the memory of the instrument in order to be familiar with
its contents and to check that it is in accordance with the standards actually supplied.
9.7 Preparation of Apparatus on All Other Occasions:
9.7.1 Flush out the measurement chamber using flushing solvent
9.7.2 Turn on the heating bath.
9.7.3 Refill the measurement chamber with Non-Newtonian Reference Oil RL 232.
9.7.4 Leave for not less than half an hour for temperature to stabilise.
9.7.4.1 If the bath does not reach correct temperature in this time, then either extend this period or, preferably, address the problem
of why heating is slow.
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