ASTM D6896-12
(Test Method)Standard Test Method for Determination of Yield Stress and Apparent Viscosity of Used Engine Oils at Low Temperature
Standard Test Method for Determination of Yield Stress and Apparent Viscosity of Used Engine Oils at Low Temperature
SIGNIFICANCE AND USE
5.1 When an engine oil is cooled, the rate and duration of cooling can affect its yield stress and viscosity. In this laboratory test, used engine oil is slowly cooled through a temperature range where wax crystallization is known to occur, followed by relatively rapid cooling to the final test temperature. As in other low temperature rheological tests such as Test Methods D3829, D4684, and D5133, a preheating condition is required to ensure that all residual waxes are solubilized in the oil prior to the cooldown (that is, remove thermal memory). However, it is also known that highly sooted used diesel engine oils can experience a soot agglomerization phenomenon when heated under quiescent conditions. The current method uses a separate preheat and agitation step to break up any soot agglomerization that may have occurred prior to cooldown. The viscosity of highly sooted diesel engine oils as measured in this test method have been correlated to pressurization times in a motored engine test (1).3
5.2 Cooling Profiles:
5.2.1 For oils to be tested at -20°C and -25°C, Table X1.1 applies. The cooling profile described in Table X1.1 is based on the viscosity properties of the ASTM Pumpability Reference Oils (PRO). This series of oils includes oils with normal low-temperature flow properties and oils that have been associated with low-temperature pumpability problems (2-7).
SCOPE
1.1 This test method covers the measurement of the yield stress and viscosity of engine oils after cooling at controlled rates over a period of 43 or 45 h to a final test temperature of -20 or -25°C. The precision is stated for test temperatures -25 and -20°C. The viscosity measurements are made at a shear stress of 525 Pa over a shear rate of 0.4 to 15 s-1. This test method is suitable for measurement of viscosities ranging from 4000 mPa·s to >400 000 mPa·s, and is suitable for yield stress measurements of 7 Pa to >350 Pa.
1.2 This test method is applicable for used diesel oils. The applicability and precision to other used or unused engine oils or to petroleum products other than engine oils has not been determined.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 Exception—This test method uses the SI based unit of milliPascal second (mPa·s) for viscosity which is equivalent to centiPoise (cP).
1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D6896 − 12
StandardTest Method for
Determination of Yield Stress and Apparent Viscosity of
1
Used Engine Oils at Low Temperature
This standard is issued under the fixed designation D6896; 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.
1. Scope* D5133 Test Method for Low Temperature, Low Shear Rate,
Viscosity/Temperature Dependence of Lubricating Oils
1.1 This test method covers the measurement of the yield
Using a Temperature-Scanning Technique
stress and viscosity of engine oils after cooling at controlled
E1137 SpecificationforIndustrialPlatinumResistanceTher-
rates over a period of 43 or 45 h to a final test temperature of
mometers
-20 or -25°C. The precision is stated for test temperatures -20
and -25°C. The viscosity measurements are made at a shear
3. Terminology
-1
stress of 525 Pa over a shear rate of 0.4 to 15 s . This test
3.1 Definitions:
method is suitable for measurement of viscosities ranging from
3.1.1 apparent viscosity, n—the determined viscosity ob-
4000 mPa·s to >400 000 mPa·s, and is suitable for yield stress
tained by use of this test method.
measurements of 7 Pa to >350 Pa.
3.1.2 Digital Contact Thermometer (DCT), n—an electronic
1.2 This test method is applicable for used diesel oils. The
device consisting of a digital display and associated tempera-
applicability and precision to other used or unused engine oils
ture sensing probe.
or to petroleum products other than engine oils has not been
3.1.2.1 Discussion—This device consists of a temperature
determined.
sensor connected to a measuring instrument; this instrument
1.3 The values stated in SI units are to be regarded as
measures the temperature-dependent quantity of the sensor,
standard. No other units of measurement are included in this
computes the temperature from the measured quantity, and
standard.
provides a digital output or display of the temperature, or both.
1.3.1 Exception—This test method uses the SI based unit of
The temperature sensing probe is in contact with the material
milliPascal second (mPa·s) for viscosity which is equivalent to
whose temperature is being measured. This device is some-
centiPoise (cP).
times referred to as a digital thermometer.
1.4 This standard does not purport to address all of the
3.1.3 Newtonian oil or fluid, n—anoilorfluidthatatagiven
safety concerns, if any, associated with its use. It is the
temperature exhibits a constant viscosity at all shear rates or
responsibility of the user of this standard to establish appro-
shear stresses.
priate safety and health practices and determine the applica-
3.1.4 non-Newtonian oil or fluid, n—an oil or fluid that at a
bility of regulatory limitations prior to use.
given temperature exhibits a viscosity that varies with chang-
2. Referenced Documents ing shear stress or shear rate.
2
3.1.5 shear rate, n—the velocity gradient in fluid flow. For
2.1 ASTM Standards:
a Newtonian fluid in a concentric cylinder rotary viscometer in
D3829 Test Method for Predicting the Borderline Pumping
which the shear stress is measured at the inner cylinder surface
Temperature of Engine Oil
(such as the apparatus described in 6.1), and ignoring any end
D4684 Test Method for Determination of Yield Stress and
effects, the shear rate is given as follows:
Apparent Viscosity of Engine Oils at Low Temperature
2
2~Ω!R
s
G 5 (1)
r 2 2
R 2 R
1
s r
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of 2
4~π!R
s
Subcommittee D02.07 on Flow Properties.
5 (2)
2 2
t ~R 2 R !
s r
Current edition approved Nov. 1, 2012. Published April 2013. Originally
approved in 2003. Last previous edition approved in 2007 as D6896–03(2007).
where:
DOI: 10.1520/D6896-12.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or G = shear rate at the surface of the rotor in reciprocal
r
-1
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
seconds, s ,
Standards volume information, refer to the standard’s Document Summary page on
Ω = angular velocity, rad/s,
the ASTM website.
*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
1
---------------------- Page: 1 ----------------------
D6896 − 12
5. Significance and Use
R = stator radius, mm,
s
R = rotor radius, mm, and
r
5.1 When an engine oil is cooled, the rate and duration of
t = time for one revolution of the rotor, s.
cooling can affect its yield stress and viscosity. In
...
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: D6896 − 03 (Reapproved 2007) D6896 − 12
Standard Test Method for
Determination of Yield Stress and Apparent Viscosity of
1
Used Engine Oils at Low Temperature
This standard is issued under the fixed designation D6896; 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.
1. Scope Scope*
1.1 This test method covers the measurement of the yield stress and viscosity of engine oils after cooling at controlled rates over
a period of 43 or 45 h to a final test temperature of -20 or -25°C. The precision is stated for test temperatures -20 and -25°C. The
-1
viscosity measurements are made at a shear stress of 525 Pa over a shear rate of 0.4 to 15 s . This test method is suitable for
measurement of viscosities ranging from 4000 mPa·s to >400 000 mPa·s, and is suitable for yield stress measurements of 7 Pa to
>350 Pa.
1.2 This test method is applicable for used diesel oils. The applicability and precision to other used or unused engine oils or
to petroleum products other than engine oils has not been determined.
1.3 This test method uses the millipascal second (mPa·s) as the unit of viscosity. For information, the equivalent centipoise unit
is shown in parentheses.The values stated in SI units are to be regarded as standard. No other units of measurement are included
in this standard.
1.3.1 Exception—This test method uses the SI based unit of milliPascal second (mPa·s) for viscosity which is equivalent to
centiPoise (cP).
1.4 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
D3829 Test Method for Predicting the Borderline Pumping Temperature of Engine Oil
D4684 Test Method for Determination of Yield Stress and Apparent Viscosity of Engine Oils at Low Temperature
D5133 Test Method for Low Temperature, Low Shear Rate, Viscosity/Temperature Dependence of Lubricating Oils Using a
Temperature-Scanning Technique
E1137 Specification for Industrial Platinum Resistance Thermometers
3. Terminology
3.1 Definitions:
3.1.1 apparent viscosity—viscosity, n—the determined viscosity obtained by use of this test method.
3.1.2 Digital Contact Thermometer (DCT), n—an electronic device consisting of a digital display and associated temperature
sensing probe.
1
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.07 on
Flow Properties.
Current edition approved Nov. 1, 2007Nov. 1, 2012. Published January 2008April 2013. Originally approved in 2003. Last previous edition approved in 20032007 as
ε1
D6896D6896–03(2007).–03 . DOI: 10.1520/D6896-03R07.10.1520/D6896-12.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3.1.2.1 Discussion—
This device consists of a temperature sensor connected to a measuring instrument; this instrument measures the temperature-
dependent quantity of the sensor, computes the temperature from the measured quantity, and provides a digital output or display
*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
1
---------------------- Page: 1 ----------------------
D6896 − 12
of the temperature, or both. The temperature sensing probe is in contact with the material whose temperature is being measured.
This device is sometimes referred to as a digital thermometer.
3.1.3 Newtonian oil or fluid—fluid, n—an oil or fluid that at a given temperature exhibits a constant viscosity at all shear rates
or shear stresses.
3.1.4 non-Newtonian oil or fluid—fluid, n—an oil or fluid that at a given temperature exhibits a viscosity that varies with
changing shear stress or shear rate.
3.1.5 shear rate—rate, n—the velocity gradient in fluid flow. For a Newtonian fluid in a concentric cylinder rotary viscometer
in which the shear stress is measured at the inner cy
...
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