Lubricating oil compositions

A lubricating oil composition comprising (a) a major amount of an oil of lubricating viscosity selected from the group consisting of Group I, II, III and IV basestocks, and mixtures thereof, and (b) an oil-soluble tetra-functional hydrolyzable silane compound of formula I or a hydrolysis product thereof:

• wherein a is an integer from 1 to 4 and each R is independently a C1 to C6 alkoxy group, C6 to C20 aryloxy group, C6 to C20 alkylaryloxy group, C6 to C20 arylalkyloxy group, C6 to C20 cycloalkyloxy group, C6 to C20 cycloalkylalkyloxy group, and C6 to C20 alkylcycloalkyloxy group, and further wherein the lubricating oil composition is free of any zinc dialkyl dithiophosphate compound and has a wear scar diameter greater than or equal to a corresponding lubricating oil composition in which the oil-soluble tetra-functional hydrolyzable silane compound in the lubricating oil composition is replaced with a zinc dialkyl dithiophosphate compound as measured by using an AISI 52100 steel pin (φ6.2 mm×11 mm, HRC 60-64) driven by a motor to reciprocate over a steel disc (φ19 mm×4 mm, HRC 60-64, polished to a mirror finish using 3 μm diamond paste) in a pin-on-disc configuration;
• wherein prior to commencing the measurement, about 30 mL of a lubricating oil composition was introduced into a steel disc holder;
• and wherein the sliding was carried out at a frequency of 25 Hz, stroke of 7 mm, load of 220 N, and a temperature of 100° C., for a duration of 1 hour.