A Mechanism of Needle Crystal Formation by Magnesium Detergents in Engine Oils

Some magnesium detergents in engine oil are reported to form sludge of needle crystals in the presence of carbon dioxide and water We tried to reproduce needle crystals in a beaker test and studied factors in needle crystal formation by magnesium detergents We found that overbased components of magnesium detergents dissolved in carbonic acid water formed needle crystals recrystallizing We also found the quantities of needle crystals increased when both carbon dioxide and water content in oil increased Moreover we clarified the quantities and sizes of needle crystals differed by magnesium detergents