Figure 8. Sulfur Compounds from Oil
Extending lubricant life is important both for economic and environmental reasons, since
downtime for oil changes is costly for truckers and lubricating oil is the single worst liquid
contaminant in landfills. Approaches to achieve lubricant life extension could include the
development of oil-quality sensors, which could be used to prevent premature oil changes, and
development of improved biodegradable lubricants. Current vegetable oils have good friction
and wear properties but low oxidation stability and poor low-temperature behavior.
Looking farther into the future, a number of alternative lubricant concepts are being considered,
including the following:
A consumable lubricant, which would burn with the fuel and thus not need to be
drained; new oil would just be added as needed.
Partitioning the engine so that an optimal lubricant could be developed for each
Conversely, developing a universal lubricant that could be used in transmissions and
axles as well as in the engine.
Developing new lubricants that are compatible with advanced materials and coatings
or, conversely, developing advanced materials and coatings that do not require liquid
An interesting compatibility problem has retarded past developments of lubricants. This has
occurred because any new lubricant has been required to be compatible with old hardware, and
new hardware developments have been limited by compatibility with current or old lubricants.
Most rapid progress could be made if the lubricant were considered as a design variable
simultaneously with the materials and mechanical design.