DEVELOPMENT OF A BENCH-SCALE TEST TO EVALUATE LUBRICANTS FOR USE WITHMETHANOL-FUELED ENGINES

In methanol-fueled diesel engines, the crankcase lubricant is used to lubricate both the engine and the fuel injector system. Crankcase lubr icants including some designed for methanol-fueled engines are not com pletely compatible with the methanol fuel. In oder to test the effect of methanol extraction on diesel engine lubricant performance, two ext raction protocols were developed: one to simulate the fuel injector (1 000 parts of methanol to one part of lubricant) and the other to simul ate an extreme case of methanol contamination in the crankcase (one pa rt of methanol to five parts of lubricant). The extracted samples of t he lubricant were stripped to remove the methanol. The samples were th en evaluated for changes in oxidative stability and lubricity. The sam ples produced from these extraction procedures were evaluated In the P enn State microoxidation test for oxidative stability and in a microsa mple sequential four-ball wear test designed to use 0.2 ml of the lubr icant per test. Two lubricants designed for use in the methanol-fueled engines were evaluated in this study to demonstrate some of the poten tial problems for lubricants used in methanol-fueled engines. Since bo th the base oil and the additives can be separated by methanol contami nation, it is important that both the extract (methanol soluble) and t he raffinate (methanol insoluble) fractions of the base oil supply ade quate solubility for the portion of the additives found In each fracti on. The test protocol developed was found to be capable of being a pre cursor evaluation technique for testing lubricants for use in a methan ol-fueled engine.