EFFECT OF ADDITION AGENTS IN LUBRICATING OIL ON PISTON AND RING PERFORMANCE IN GASOLINE AND DIESEL ENGINES

With the increase in horsepower output per cubic inch displacement, gasoline and Diesel engines are more susceptible to ring sticking and piston ring or cylinder liner wear. Formerly crank case oil stability (how the used oil looked when drained after 50 hours or more operation in an engine) was considered of prime importance. It was thought that the tendency of mineral oils to cause ring sticking depended largely on the degree of refinement of the lubricating oil, but this has not proven to be the case with Diesel engines or with high output gasoline engines. Highly solvent treated oils have been shown to be deficient in lubricating value and ring sticking caused by excessive blowby has resulted. Such high output gasoline and Diesel engines will operate on straight mineral oils at reduced loads; but reduced cylinder wear, freedom from ring sticking and sludge reduction can be had only with proven addition agents. The highly refined paraffinic base oils plus oiliness addition agents are the most effective for high output gasoline engines, whereas the naphthenic base oils plus entirely different addition agents are best suited for Diesel engines.

High output gasoline and Diesel engine research has shown that a lubricant to reduce ring and cylinder liner wear and give freedom from ring sticking, should consist of a very stable vehicle plus an addition agent which has proper film strength and adhesion, as well as resistance to corrosion and oxidation.