A DETAILED report of the results obtained testing hypoid lubricants at the Chevrolet Motor Co. is presented in this paper. As a result of these tests it is announced that 182 hypoid lubricants have been put on the Chevrolet approved list.
Seeking to correct an impression that only lead soap-active sulphur and lead soap-sulphur saponifiable-chlorine lubricants would be considered, the author states that other types that meet specifications also will be put on the approved list.
Nine different characteristics are checked in the laboratory tests: load-carrying properties; viscosity; chemical analysis to determine the total lead, sulphur, and chlorine; oxidation; evaporation loss; non-combustible sediment; channeling; foaming; and copper-strip test.
Scoring tests were conducted over a 3.8-mile speed loop in the proving ground at speeds varying from 10 to 70 m.p.h., and a new third member was used for each test of each lubricant. If the lubricant prevented scoring in two tests and was free from certain undesirable characteristics as determined in the laboratory, it was considered satisfactory.
Hypoid lubricants that failed to pass the tests are analyzed. Durability tests on various hypoid lubricants covering mileages up to 40,000 are described.