The Effects of Lubricant Composition on S.I. Engine Wear With Alcohol Fuels

An investigation of the effects of lubricant composition changes on spark ignition engine wear and deposits when using alcohol fuel was jointly sponsored by the U.S. Department of Energy and the U.S. Army Mobility Equipment Research and Development Command. In the work covered by this paper, tests were conducted with methanol fuel in a 2.3-liter engine using a modified ASTM Sequence V-D procedure. The baseline lubricant was a 10W-30 grade product, qualified under MIL-L-46152, for which a large amount of field and laboratory data were available. Eleven variations of the baseline lubricant were supplied and tested. The results indicate that a magnesium-based detergent additive was less effective in controlling methanol-related engine wear than was a calcium-based additive. Ashless dispersant chemistry was also determined to be of importance in controlling wear with methanol fuel. Experiments were conducted to identify the wear mechanism using the 2.3-liter engine, 20-hour steady-state test. This 20-hour test shows promise as a lubricant screening procedure when using methanol fuel.