NAVFAC P-300 Management of Transportation Equipment

3. Grease Lubricants. A lubricating grease is a solid to semifluid mixture of a fluid
lubricant and thickening agent. Additives that give special properties may be
incorporated. The fluid component may be a mineral oil or a synthetic fluid; the
thickener may be a metallic soap or a nonsoap substance such as clay, a urea
compound, or other material. The most commonly used soaps are calcium, lithium,
sodium, aluminum or a combination of these with other materials. When mixing
different types of greases, the possibility of incompatibility exists and should be
avoided since it may result in excessive thinning and leakage. Cleanliness is the prime
consideration in the use of greases. The removal of surface grease and dirt
accumulation from dispensing equipment and application points such as zerks and
grease gun fitting is essential. Excessive dispensing pressures and pumping rates
should be avoided because they tend to cause seal deformation and rupture.
Automotive service greases are classified into two groups: (1) chassis lubricants
and (2) wheel bearing lubricants. These are further separated into performance
categories: chassis grease categories "LA" and "LB," and wheel bearing grease
categories "GA," "GB," and "GC." Greases that meet the requirements of chassis
grease and wheel bearing grease are considered multipurpose greases, and should
carry the appropriate NLGI designations for both groups to avoid confusion with
commercial, nonautomotive multipurpose greases.
a. National Lubrication Grease Institute (NLGI) Classifications. A list of the
NLGI classifications is shown below.
(1) LA service is typical of chassis components and universal joints in
passenger cars, trucks, and other vehicles under mild duty only. Mild duty is
encountered in vehicles operated with frequent relubrication in non-critical applications.
(2) LB service is typical of chassis components and universal joints in
passenger cars, trucks, and other vehicles under mild to severe duty. Severe duty is
encountered in vehicles operated under conditions which may include prolonged
relubrication intervals, or high loads, severe vibration, exposure to water or other
contaminants.
(3) GA service is typical of wheel bearings in passenger cars, trucks,
and other vehicles under mild duty. Mild duty is encountered in vehicles operated with
frequent relubrication in non-critical applications.
(4) GB service is typical of wheel bearings in passenger cars, trucks,
and other vehicles under mild to moderate duty. Moderate duty is encountered in most
vehicles operated under normal urban, highway, and off-highway service.
(5) GC service is typical of wheel bearings in passenger cars, trucks,
and other vehicles under mild to severe duty. Severe duty is encountered in certain
vehicles operated under conditions that result in high bearing temperatures. This
includes vehicles operated under frequent stop-and-go service (buses, taxis, urban
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