ASTM D4950 Standard Classification and Specification for Automotive Service Greases
1. Scope
1.1 This specification covers lubricating greases suitable for the periodic relubrication of chassis systems and wheel bearings of passenger cars, trucks, and other vehicles.

1.2 This specification defines the requirements used to describe the properties and performance characteristics of chassis greases and wheel bearing greases for service-fill applications.

1.3 The test requirements (acceptance limits) given in this specification are, as the case may be, minimum or maximum acceptable values for valid duplicate test results. Apply no additional corrections for test precision, such as described in Practice D3244, inasmuch as the precision of the test methods was taken into account in the determination of the requirements.

1.4 The values stated in SI units are to be regarded as standard.
1.4.1 Exceptions - Test Method D2596 reports test results in kgf units, and Test Method D4289 reports rubber hardness in Durometer Shore A units.

2. Referenced Documents
2.1 ASTM Standards:
D217 Test Methods for Cone Penetration of Lubricating Grease
D566 Test Method for Dropping Point ofLubricating Grease
D1264 Test Method for Determining the Water Washout Characteristics of Lubricating Greases
D1742 Test Method for Oil Separation from Lubricating Grease During Storage
D1743 Test Method for Determining Corrosion Preventive Properties of Lubricating Greases
D2265 Test Method for Dropping Point of Lubricating Grease Over Wide Temperature Range
D2266 Test Method for Wear Preventive Characteristics of Lubricating Grease (Four-Ball Method)
D2596 Test Method for Measurement of Extreme-Pressure Properties of Lubricating Grease (Four-Ball Method)
D3244 Practice for Utilization of Test Data to Determine Conformance with Specifications
D3527 Test Method for Life Performance of Automotive Wheel Bearing Grease
D4170 Test Method for Fretting Wear Protection by Lubricating Greases
D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants
D4289 Test Method for Elastomer Compatibility of Lubricating Greases and Fluids
D4290 Test Method for Determining the Leakage Tendencies of Automotive Wheel Bearing Grease Under Accelerated Conditions
D4693 Test Method for Low-Temperature Torque of Grease-Lubricated Wheel Bearings

2.2 SAE Standards:
AMS 3217A Standard Elastomer Stock-Test Slabs
AMS 3217/2C Test Slabs, Acrylonitrile Butadiene (NBR-L)-Low Acrylonitrile, 65-75
AMS 3217/3B Test Slabs Chloroprene (CR)-65-75
SAE J310 Automotive Lubricating Greases

3. Terminology
3.1 Definitions:
3.1.1 lubricant, n - any material interposed between two surfaces that reduces the friction or wear between them.

3.1.2 lubricating grease, n - a semi-fluid to solid product of a dispersion of a thickener in a liquid lubricant.
3.1.2.1 Discussion - The dispersion of the thickener forms a two-phase system and immobilizes the liquid lubricant by surface tension and other physical forces. Other ingredients imparting special properties are often included.

3.1.3 thickener, n - in lubricating grease, a substance composed of finely-divided particles dispersed in a liquid to form the product's structure.
3.1.3.1 Discussion - The thickener can be fibers (such as various metallic soaps) or plates or spheres (such as certain non-soap thickeners) which are insoluble or, at the most, only very slightly soluble in the liquid lubricant. The general requirements are that the solid particles be extremely small, uniformly dispersed, and capable of forming a relatively stable, gel-like structure with the liquid lubricant.

3.2 Definitions of Terms Specific to This Standard:
3.2.1 automotive service grease, n - a lubricating grease suitable for the periodic relubrication of serviceable-type, chassis components or wheel bearings of passenger cars, trucks, and other vehicles and distinct from factory-fill greases (also known as initial-fill and OEM greases) initially installed by the original equipment manufacturer.

3.2.2 category, n - with respect to automotive service grease, a designation, such as LB, GC, etc., for a given level of performance in standardized tests.

3.2.3 chassis grease, n - an automotive service grease used to lubricate ball joints, steering pivots, universal joints, and, other lubrication points designated in the vehicle owner's service guide.

3.2.4 classification, n - with respect to automotive service grease, the systematic arrangement into categories according to differing levels of performance.

3.2.5 "G" category group, n - automotive service greases of such composition, properties, and performance characteristics as to be suitable for the service lubrication of those types of wheel bearings that require periodic relubrication.

3.2.6 "L" category group, n - automotive service greases of such composition, properties, and performance characteristics as to be suitable for the service lubrication of those types of suspension, steering, and drive-line components that require periodic relubrication.

3.2.7 multipurpose grease, n - an automotive service grease suitable for both chassis and wheel bearing lubrication.
3.2.7.1 Discussion - Commercial lubricating greases other than automotive service greases are often designated as multipurpose greases.

3.3 Abbreviations:
3.3.1 ASTM - American Society for Testing and Materials
3.3.2 NLGI - National Lubricating Grease Institute
3.3.3 SAE - Society of Automotive Engineers