Effect of Ventilation and Lubricants on Sludge Formation in Passenger Car Gasoline Engines

A bench test has been developed for the estimation of sludge formation. The bench test results along with engine test data reveal the following Conclusions. (1) The largest sludge formation occurs under the combination of low oil temperature/low engine speed and high oil temperature/moderate engine speed. (2) Sludge formation is greatly influenced by the ventilation in the rocker chambers and crankcase. (3) In addition to improvement in the ventilation system the use of phenol-type antioxidants, salicylate-type detergents and dispersant-type viscosity improvers was effective for sludge protection.