ASTM D6022-19

Standard Practice for Calculation of Permanent Shear Stability Index

SIGNIFICANCE AND USE
5.1 Permanent Shear Stability Index (PSSI) is a measure of the loss of viscosity, due to shearing, contributed by a specified additive.  
Note 2: For example, a PSSI of 50 means the additive will lose 50 % of the viscosity it contributes to the finished oil.  
5.2 The selection of appropriate base fluids and additive concentrations to be used in test oils is left to individual operators or companies. These choices will depend on the intended application for the additive.  
Note 3: PSSI may depend more strongly on base fluid, additive concentration, additive chemistry, and the presence of other additives for base fluids of unusual composition (for example, esters) or if additives outside the common range of chemistries and concentrations are used. Caution should be exercised when interpreting results from different sources.
SCOPE
1.1 This practice specifies the procedure for the calculation of Permanent Shear Stability Index (PSSI) of an additive using viscosities before and after a shearing procedure.  
1.2 PSSI is calculated for a single blend component and can then be used to estimate the effects of that component on finished lubricant blends.  
1.3 This practice is applicable to many products and may use data from many different test methods. The calculation is presented in its most general form in order not to restrict its use.  
1.4 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: 30-Nov-2019
• ICS: 17.060 - Measurement of volume, mass, density, viscosity
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.07 - Flow Properties

Relations

• Replaces: ASTM D6022-06(2012) - Standard Practice for Calculation of Permanent Shear Stability Index
• Effective Date: 01-Dec-2019
• Refers: ASTM D6709-24 - Standard Test Method for Evaluation of Automotive Engine Oils in the Sequence VIII Spark-Ignition Engine (CLR Oil Test Engine)
• Effective Date: 01-Mar-2024
• Refers: ASTM D6709-23 - Standard Test Method for Evaluation of Automotive Engine Oils in the Sequence VIII Spark-Ignition Engine (CLR Oil Test Engine)
• Effective Date: 01-Dec-2023
• Refers: ASTM D6278-20a - Standard Test Method for Shear Stability of Polymer Containing Fluids Using a European Diesel Injector Apparatus
• Effective Date: 01-Jun-2020
• Refers: ASTM D6278-20 - Standard Test Method for Shear Stability of Polymer Containing Fluids Using a European Diesel Injector Apparatus
• Effective Date: 01-May-2020
• Refers: ASTM D7109-20 - Standard Test Method for Shear Stability of Polymer-Containing Fluids Using a European Diesel Injector Apparatus at 30 Cycles and 90 Cycles
• Effective Date: 01-May-2020
• Refers: ASTM D5275-20 - Standard Test Method for Fuel Injector Shear Stability Test (FISST) for Polymer Containing Fluids
• Effective Date: 01-May-2020
• Refers: ASTM D2603-19 - Standard Test Method for Sonic Shear Stability of Polymer-Containing Oils
• Effective Date: 01-Jun-2019
• Refers: ASTM D5621-19 - Standard Test Method for Sonic Shear Stability of Hydraulic Fluids
• Effective Date: 01-Jun-2019
• Refers: ASTM D4485-18 - Standard Specification for Performance of Active API Service Category Engine Oils
• Effective Date: 01-Jul-2018
• Refers: ASTM D7109-18 - Standard Test Method for Shear Stability of Polymer-Containing Fluids Using a European Diesel Injector Apparatus at 30 Cycles and 90 Cycles
• Effective Date: 01-Jun-2018
• Refers: ASTM D5275-17 - Standard Test Method for Fuel Injector Shear Stability Test (FISST) for Polymer Containing Fluids
• Effective Date: 01-May-2017
• Refers: ASTM D6278-17 - Standard Test Method for Shear Stability of Polymer Containing Fluids Using a European Diesel Injector Apparatus
• Effective Date: 01-Jan-2017
• Refers: ASTM D4485-16 - Standard Specification for Performance of Active API Service Category Engine Oils
• Effective Date: 15-Dec-2016
• Refers: ASTM D5275-16 - Standard Test Method for Fuel Injector Shear Stability Test (FISST) for Polymer Containing Fluids
• Effective Date: 01-Jun-2016

Overview

ASTM D6022-19 is the Standard Practice for Calculation of Permanent Shear Stability Index (PSSI), developed by ASTM International. The standard provides a comprehensive procedure for calculating the loss of viscosity due to shearing, specifically related to additives in lubricating oils. Understanding and calculating the PSSI allows operators to evaluate the long-term viscosity retention of lubricating additives, which is crucial for the performance and durability of hydraulic fluids, automotive engine oils, and other lubricant blends subjected to mechanical stress.

This standard is widely used in the lubricant industry, helping companies ensure that their products meet performance expectations under various operational conditions.

Key Topics

• Permanent Shear Stability Index (PSSI):
  PSSI quantifies the irreversible viscosity loss contributed by a specific additive after subjecting the lubricant to shearing forces. A lower PSSI indicates higher resistance to shear-induced viscosity loss.

• Calculation Procedure:
  The standard outlines how to measure viscosities of the unsheared oil (test oil with additive), sheared oil (after imposed shear), and the base fluid (without additive). Key steps include:

  • Calculating the Degree of Thickening (DT) as the ratio of viscosity with additive to viscosity without additive.
  • Only calculating PSSI if DT is greater than or equal to 1.2 for meaningful results.
  • PSSI is then calculated using standardized equations based on viscosity differences before and after shearing.

• Viscosity Measurement:
  Measurements must be made using consistent test methods and under standardized temperature and shear conditions to ensure accuracy and comparability.

• Interpreting PSSI Results:
  The selection of base fluids, additive concentration, and chemistry can significantly impact PSSI values. Caution is advised in comparing results across different testing setups.

Applications

• Lubricant Formulation:
  PSSI is critical in formulating engine oils, hydraulic fluids, and other lubricants that incorporate viscosity index improvers or other additives. By assessing shear stability, formulators can predict product behavior in service and optimize blends for durability.

• Quality Control:
  Manufacturers use PSSI calculations to assess additive performance, ensuring consistent lubricant quality that meets industry and customer specifications.

• Testing Across Methods:
  ASTM D6022-19 is applicable regardless of the shearing method used, including bench tests, engine tests, and field service evaluations. It supports various test methods for shearing, such as:

  • Sonic shearing
  • Injector-based methods
  • Bench and engine wear tests

• Comparative Analysis:
  PSSI provides a reliable index for comparing the shear stability of different additives or formulations. This aids in the selection of additives for specific operating environments and performance needs.

Related Standards

• Referenced ASTM Standards for Testing Shear Stability and Viscosity:

  • ASTM D2603 - Sonic Shear Stability of Polymer-Containing Oils
  • ASTM D4485 - Specification for Performance of Active API Service Category Engine Oils
  • ASTM D5275 - Fuel Injector Shear Stability Test for Polymer-Containing Fluids
  • ASTM D5621 - Sonic Shear Stability of Hydraulic Fluids
  • ASTM D6278, D6709, D7109 - Various methods assessing fluid shear stability

• Relevant CEC Standards:

  • CEC L14AL-93 - Mechanical shear stability for lubricating oils
  • CEC L37 T 85, CEC L45L-99 - Shear stability of transmission and engine lubricants

These related standards provide the necessary methodologies for obtaining the viscosity data required in PSSI calculation and offer additional guidance for evaluating the shear stability of lubricants and additives.

---

By adhering to ASTM D6022-19, lubricant manufacturers and formulators ensure reliable, reproducible assessment of permanent shear stability, supporting product performance and regulatory compliance within the global lubrication industry.

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: D6022 − 19
Standard Practice for
Calculation of Permanent Shear Stability Index
This standard is issued under the fixed designation D6022; 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* D7109 Test Method for Shear Stability of Polymer-
Containing Fluids Using a European Diesel Injector Ap-
1.1 This practice specifies the procedure for the calculation
paratus at 30 Cycles and 90 Cycles
of Permanent Shear Stability Index (PSSI) of an additive using
2.2 CEC Standards:
viscosities before and after a shearing procedure.
CEC L-14-93 Evaluation of the Mechanical Shear Stability
1.2 PSSI is calculated for a single blend component and can
of Lubricating Oils Containing Polymers
then be used to estimate the effects of that component on
CEC L-45-99 Viscosity Shear Stability of Transmission
finished lubricant blends.
Lubricants (KRL)
1.3 This practice is applicable to many products and may
3. Terminology
use data from many different test methods. The calculation is
presented in its most general form in order not to restrict its
3.1 Definitions:
use. 3.1.1 degree of thickening (DT), n—the ratio of an oil’s
viscosity with an additive to that oil’s viscosity without the
1.4 This international standard was developed in accor-
additive. A measure of the amount by which an additive
dance with internationally recognized principles on standard-
increases the base fluid viscosity.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3.1.2 permanent shear stability index (PSSI), n—a measure
mendations issued by the World Trade Organization Technical
of the irreversible decrease, resulting from shear, in an oil’s
Barriers to Trade (TBT) Committee. viscosity contributed by an additive.
3.1.2.1 Discussion—PSSI is a property calculated for a
2. Referenced Documents
single component. Viscosity Loss (q.v.) is a property measured
for a finished oil.
2.1 ASTM Standards:
D2603 Test Method for Sonic Shear Stability of Polymer-
3.1.3 shear, adj—a relative movement of molecules or
Containing Oils
molecular aggregates that occurs in flowing liquids. A shear
D4485 Specification for Performance of Active API Service
flow is one in which the spatial velocity gradient is perpen-
Category Engine Oils
dicular to the direction of flow.
D5275 Test Method for Fuel Injector Shear Stability Test
3.1.3.1 Discussion—Not all flow geometries meet this defi-
(FISST) for Polymer Containing Fluids
nition.
D5621 Test Method for Sonic Shear Stability of Hydraulic
3.1.4 shear, v—to subject a liquid to a shear flow.
Fluids
3.1.4.1 Discussion—Shearing an oil can sometimes cause
D6278 Test Method for Shear Stability of Polymer Contain-
scission of certain molecular species, resulting in a decrease in
ing Fluids Using a European Diesel Injector Apparatus
viscosity. Not all oils exhibit this response. Common ways of
D6709 Test Method for Evaluation of Automotive Engine
shearing oils to elicit this effect include injection through a
OilsintheSequenceVIIISpark-IgnitionEngine(CLROil
small orifice and flow through gears or bearings. Irradiation
Test Engine)
with sonic energy can also decrease the viscosity of some oils.
3.1.5 Viscosity Loss (VL), n—a measure of the decrease in
an oil’s viscosity.
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
3.1.5.1 Discussion—Viscosity Loss is a property measured
mittee D02.07 on Flow Properties.
for a finished oil. Permanent Shear Stability Index (q.v.)isa
Current edition approved Dec. 1, 2019. Published January 2020. Originally
property calculated for a single component. Some test methods
approved in 1996. Last previous edition approved in 2012 as D6022 – 06 (2012).
report VL as a relative change, which is dimensionless (for
DOI: 10.1520/D6022-19.
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 Available from Organization for Economic Cooperation and Development,
the ASTM website. Madou Plaza, Place Madou 1, B-1030 Brussels, Belgium.
*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
D6022 − 19
example, Test Methods D2603, D5275, D6278, and D7109). 6. Procedure
Some test methods and specifications report VL as an absolute
6.1 Calculate the degree of thickening:
change, which has the same dimensions as the viscosity
DT 5 V /V (1)
0 b
measurements (for example, Specification D4485 and Test
Method D5621 and D6709).
where:
3.2 Definitions of Terms Specific to This Standard: V = viscosity of the unsheared oil, and
V = viscosity of the base fluid.
3.2.1 base fluid, n—an oil without the additive whose PSSI
b
is to be determined. The base fluid shall have a viscosity loss
6.1.1 Viscosities shall be measured using the same test
of zero, within the precision of the shearing test used.
method at the same conditions of temperature and shear rate or
3.2.1.1 Discussion—A base fluid could be a mineral oil, a
shear stress and reported in the same units.
synthetic oil, a formulation containing additives, or other
6.2 If the degree of thickening is less than 1.2, PSSI cannot
system meeting the requirement of zero viscosity loss.
be determined from these data.
3.2.2 sheared oil, n—the test oil, after shearing.
NOTE 4—Once PSSI has been determined for an additive, calculations
3.2.3 test oil, n—base fluid with the additive whose PSSI is
using that PSSI can be made for oil blends where the degree of thickening
to be determined.
is less than 1.2.
3.2.4 unsheared oil, n—the test oil, prior to shearing.
6.3 Ifthedegreeofthickeningisgreaterthanorequalto1.2,
calculate PSSI using the equation:
4. Summary of Practice
PSSI 5 100 3 V 2 V / V 2 V (2)
~ ! ~ !
0 s 0 b
4.1 An index is calculated representing the change, due to
where:
shearing,inanadditive’scontributiontoalubricant’sviscosity.
PSSI = Permanent Shear Stability Index,
A low index represents high resistance to permanent change.
V = viscosity of the unsheared oil,
4.2 Oils can be sheared by many means, including bench
V = viscosity of the sheared oil, and
s
tests designed for that purpose, engine tests, and field service.
V = viscosity of the base fluid.
b
A PSSI can be calculated for each. These indices can be used
6.3.1 Viscosities shall be measured using the same test
to compare the shearing severity of each test.
method at the same conditions of temperature and shear rate or
shear stress and reported in the same units.
NOTE 1—Some methods, especially engine tests and field service, may
include conditions where other effects (for example, evaporative loss,
NOTE 5—If V is close in value to V , that is if the degree of thickening
b 0
oxidation, fuel dilution, soot accumulation, and so forth
...

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: D6022 − 06 (Reapproved 2012) D6022 − 19
Standard Practice for
Calculation of Permanent Shear Stability Index
This standard is issued under the fixed designation D6022; 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 practice specifies the procedure for the calculation of Permanent Shear Stability Index (PSSI) of an additive using
viscosities before and after a shearing procedure.
1.2 PSSI is calculated for a single blend component and can then be used to estimate the effects of that component on finished
lubricant blends.
1.3 This practice is applicable to many products and may use data from many different test methods. The calculation is presented
in its most general form in order not to restrict its use.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
D2603 Test Method for Sonic Shear Stability of Polymer-Containing Oils
D4485 Specification for Performance of Active API Service Category Engine Oils
D5119 Test Method for Evaluation of Automotive Engine Oils in the CRC L-38 Spark-Ignition Engine (Withdrawn 2003)
D5275 Test Method for Fuel Injector Shear Stability Test (FISST) for Polymer Containing Fluids
D5621 Test Method for Sonic Shear Stability of Hydraulic Fluids
D6278 Test Method for Shear Stability of Polymer Containing Fluids Using a European Diesel Injector Apparatus
D6709 Test Method for Evaluation of Automotive Engine Oils in the Sequence VIII Spark-Ignition Engine (CLR Oil Test
Engine)
D7109 Test Method for Shear Stability of Polymer-Containing Fluids Using a European Diesel Injector Apparatus at 30 Cycles
and 90 Cycles
2.2 CEC Standards:
CEC L14AL-14-93 93 Evaluation of the Mechanical Shear Stability of Lubricating Oils Containing Polymers
CEC L37 T 85 Shear Stability of Polymer-Containing Oils (FZG)
CEC L45L-45-99 T 93 Viscosity Shear Stability of Transmission Lubricants (KRL)
3. Terminology
3.1 Definitions:
3.1.1 degree of thickening (DT), n—the ratio of an oil’s viscosity with an additive to that oil’s viscosity without the additive.
A measure of the amount by which an additive increases the base fluid viscosity.
3.1.2 permanent shear stability index (PSSI), n—a measure of the irreversible decrease, resulting from shear, in an oil’s
viscosity contributed by an additive.
3.1.2.1 Discussion—
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.07 on Flow Properties.
Current edition approved Nov. 1, 2012Dec. 1, 2019. Published November 2012January 2020. Originally approved in 1996. Last previous edition approved in 20062012
as D6022D6022 – 06 (2012).–06. DOI: 10.1520/D6022-06R12.10.1520/D6022-19.
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 Organization for Economic Cooperation and Development, Madou Plaza, Place Madou 1, B-1030 Brussels, Belgium.
*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
D6022 − 19
PSSI is a property calculated for a single component. Viscosity Loss (q.v.) is a property measured for a finished oil.
3.1.3 shear, adj—a relative movement of molecules or molecular aggregates that occurs in flowing liquids. A shear flow is one
in which the spatial velocity gradient is perpendicular to the direction of flow.
3.1.3.1 Discussion—
Not all flow geometries meet this definition.
3.1.4 shear, v—to subject a liquid to a shear flow.
3.1.4.1 Discussion—
Shearing an oil can sometimes cause scission of certain molecular species, resulting in a decrease in viscosity. Not all oils exhibit
this response. Common ways of shearing oils to elicit this effect include injection through a small orifice and flow through gears
or bearings. Irradiation with sonic energy can also decrease the viscosity of some oils.
3.1.5 Viscosity Loss (VL), n—a measure of the decrease in an oil’s viscosity.
3.1.5.1 Discussion—
Viscosity Loss is a property measured for a finished oil. Permanent Shear Stability Index (q.v.) is a property calculated for a single
component. Some test methods report VL as a relative change, which is dimensionless (for example, Test Methods D2603, D5275,
D6278, and D7109). Some test methods and specifications report VL as an absolute change, which has the same dimensions as
the viscosity measurements (for example, Specification D4485 and Test MethodsMethod D5119D5621 and D5621D6709).
3.2 Definitions of Terms Specific to This Standard:
3.2.1 base fluid, n—an oil without the additive whose PSSI is to be determined. The base fluid shall have a viscosity loss of zero,
within the precision of the shearing test used.
3.2.1.1 Discussion—
A base fluid could be a mineral oil, a synthetic oil, a formulation containing additives, or other system meeting the requirement
of zero viscosity loss.
3.2.2 sheared oil, n—the test oil, after shearing.
3.2.3 test oil, n—base fluid with the additive whose PSSI is to be determined.
3.2.4 unsheared oil, n—the test oil, prior to shearing.
4. Summary of Practice
4.1 An index is calculated representing the change, due to shearing, in an additive’s contribution to a lubricant’s viscosity. A
low index represents high resistance to permanent change.
4.2 Oils can be sheared by many means, including bench tests designed for that purpose, engine tests, and field service. A PSSI
can be calculated for each. These indices can be used to compare the shearing severity of each test.
NOTE 1—Some methods, especially engine tests and field service, may include conditions where other effects (for example, evaporative loss, oxidation,
fuel dilution, soot accumulation, and so forth.) contribute to viscosity changes. The PSSI calculated from these types of service may not be representative
of pure shearing.
4.2.1 ASTM tests commonly used to shear oils include Test Methods D2603, D5275, D5621, D6278, and D7109, among others.
4.2.2 Other standards organizations publish test methods which may be suitable for shearing oils.
4.2.3 An engine test, Test Method D5119, is also commonly used to shear oils and establish a PSSI for additives.
5. Significance and Use
5.1 Permanent Shear Stability Index (PSSI) is a measure of the loss of viscosity, due to shearing, contributed by a specified
additive.
NOTE 2—For example, a PSSI of 50 means the additive will lose 50 % of the viscosity it contributes to the finished oil.
5.2 The selection of appropriate base fluids and additive concentrations to be used in test oils is left to individual operators or
companies. These choices will depend on the intended application for the additive.
CEC L14A 93, CEC L37T 85, L-14-93 and CEC L45T 93, L-45-99, for example.
...