ENVIRONMENTAL-EFFECTS OF CRANKCASE-LUBRICATION AND MIXED-LUBRICATION

In a recent article in this journal [79 (1989) 1-23], R. Vazquez-Duhalt concludes that used motor oil is a very dangerous polluting product and that it is causing a serious environmental problem. In this article we will look at this problem by following the path of the oil through the engine and into the environment. In a crankcase-lubricated engine, contaminants such as polycyclic aromatic hydrocarbons (PAH) accumulate in the oil by a factor of up to 1000. This highly dangerous material leaves the engine in various ways, such as via particulates, oil leaks and uncontrolled oil changes, and then tends to accumulate again in the environment. By contrast, there are no such accumulation effects with a mixed-lubricated engine, which can be run on readily degradable lubricants. The application of modern mixed-lubrication systems should therefore be considered in the design and development of new engines, also for those traditionally equipped with crankcase-lubrication until now. This would solve the waste oil problem, which might well be more serious than the problems caused by gaseous exhaust emissions on which environmentalists and governments have so far been concentrating. © 1990.