ABSTRACT
This chapter is concerned with lubricants for internal combustion engines, which are gasoline or diesel fueled, as opposed to those with turbine or hydraulic drives. The engine parts must be protected from corrosion by water or by the oil. An internal combustion engine requires lubrication in distinct areas. The mechanisms of engine lubrication fall into two regimes: hydrodynamic in the bearings, and boundary layer in the pistons and valves. Oil takes two paths through an engine. All the oil pumped, sprayed, or splashed onto surfaces in the engine drains by gravity back down to the bottom of the engine and the oil pan, to be picked up again by the pump. The lowered friction of contact does not affect the viscous component of the energy losses, but it should affect engine power output and fuel economy by reducing boundary layer energy losses. Vegetable oil based motor oils have been successfully demonstrated in gasoline engine fleets.
