Sludge deposits in internal combustion engines can indicate either lack of proper maintenance, too high oil temperature or oil contamination. Change your engine oil regularly to avoid costly repairs. If your engine already has oil sludge do not use any type of engine flush, unless you are planning to remove the engine oil pan to get all the sludge out of the engine. Doing an engine flush without removing the oil pan could damage your engine due to lack of lubrication. The oil strainer could get clogged and and starve the oil pump and and rest of the engine.