Proper lubrication is an important factor in reducing wear and preventing premature failure of truck components. The oil film provided by lubricants between moving parts reduces friction, prevents excessive heat, and holds dirt particles in suspension. Lubricants also contain additives that inhibit corrosion and aid in reducing component wear. Heat and use alter the chemical properties of lubricants, making regular lubricant change intervals necessary. In later chapters of this book, lubricants and lubrication are discussed in the context of specific systems. Actually, the proper use of lubricants is the backbone of most good fleet PM programs. Meeting the lubrication requirements of a vehicle is not difficult. It requires adhering to the manufacturer’s recommendations provided in the service literature. However, there are some other factors to consider—especially in fleets made up of different OEM chassis and mixed component brands. In some cases, manufacturers approve several types of lubricants (such as engine oil or gear lubricants in transmissions and final drive carriers).
Synthetic lubricants are tending to replace mineralbased lubes in transmissions, differential carriers, and wheel ends because service intervals can be greatly extended. Also critical is the lube viscosity. When should a 90-weight, 140-weight, or multiviscosity lubricant be used? How does gear lube viscosity compare with engine oil viscosity? To perform a proper lubrication job, the service technician should have some understanding of lubricant properties and the lubrication requirements of chassis components.