Search Results

Automotive gear oil development has expanded beyond the historical requirements of emphasizing wear protection to encompass modern needs for fuel economy and limited slip frictional properties. This paper describes the development process of a new generation, fuel efficient gear lubricant for use in light duty vehicles. A systematic formulation approach was used, encompassing fluid viscometrics and additive optimization. Performance testing in both laboratory and vehicle tests is described. Though standard GL-5 tests were used to confirm oxidation, wear and corrosion performance, emphasis is given to those methods used for optimizing fuel economy.

The presence of water in lubricants can cause a variety of quality and performance problems (1). Depending on the lubricant type and application, excessive water can cause additive fall out or hydrolysis, corrosion and pitting of metal surfaces during use, interference with surface active additives such as friction modifiers, foaming of the lubricant and filter plugging. Quality checks for water are commonly done using techniques such as visual inspection, crackle test, measurement of dielectric breakdown voltage (2) or Karl Fischer titration (3). Of these, only Karl Fischer titration is truly quantitative. Quantitation of water can be complicated by the presence of hydrophilic additives, which attract and bind water. Fourier Transform Infrared Spectroscopy (FTIR) can be used as a screening test because the presence of water will cause a broad absorbance peak to appear at about 3400 cm-1 due to the OH stretch.