Paraffin And Motor Oils

Few, if any, misconceptions about motor oils have been so widely circulated as this one: "motor oils containing paraffin can leave deposits in engines." No one seems to know how this misconception got started, but it sometimes appears to have taken on a life of its own.

Most major motor oils today are formulated using paraffin-based crude oil. And they do not leave behind deposits in engines. In fact, one of the reasons paraffin-based oils are used is to insure against deposits. The confusion apparently begins with the fact that our first introduction in life to paraffin is as a wax.

When motor oil chemists speak of paraffin they are referring to relatively non-reactive hydrocarbons, extracted from crude oil, which have excellent oxidation stability. That stability prevents oils from breaking down under extreme operating temperatures and as a result are unlikely to form deposits.

Motor oils not formulated from paraffin-based oils use naphthenic-based crude oils and are more likely to leave deposits in engines.