Lubricating Oil Compositions with Engine Wear Protection
A method for improving wear control of a steel surface lubricated with a lubricating oil through the generation of thick tribofilms. The method includes: (i) using as the lubricating oil a formulated oil, the formulated oil having a composition comprising at least one lubricating oil base stock as a major component; and at least one lubricating oil additive, as a minor component; and (ii) forming a tribofilm on the steel surface. In time-step tribofilm formation measurements of the lubricating oil by a mini-traction machine (MTM) at constant slide-to-roll ratio (SRR), the saturation traction coefficient (fs), which correlates to tribofilm thickness on the steel surface, is greater than about 0.11. In the method of this disclosure, elongation of timing chain due to wear of chain link pins is less than about 0.07%, as determined by Ford Chain Wear (FCW) test conducted in accordance with ILSAC GF-6 specification. The lubricating oils are useful in internal combustion engines.