if you really want to clean your engine, the safest and best way to do it is to flush it with engine oil...i used cheap engine oil (API-SE SAE 40) to flush my civic's engine before i poured the Fully Synthetic oil...i would recommend owners to flush their engines(specially diesel ones) with ENGINE OIL once every 40,000 km or once a year whichever comes first...

i know little about cans of motor oil flush that you can buy in store shelves...i read somewhere that they are "chemical" based(if I remember it right, it has a very strong smell)...it may not be harmful to the engine's ferrous components but they may be harmful to the oil seals...

vinj, is right...Caltex has a flushing OIL...Caltex Power Flushing Oil is a mineral based oil with a detergent-dispersant additiveengine oil additives and function booster to effectively flush the lubrication systems of both gasoline and diesel engines. Sometimes the detergent and dispersant content in our favorite engine oil is not enough to counter the effects of sludge formation. Remember, sludge fills the piston grooves and interferes with the piston ring operation. It will cause blow-by combustion gases into the crankcase(more soot) and will allow oil to by-pass the piston rings(oil consumption). Increased blow-by causes fuel dilution fo the oil in the crankcase, thinning the engine oil and contributing to wear of vital engine components. So you see, it is not bad to flush your engine once in a while. YOU JUST HAVE TO USE THE RIGHT MATERIALS.

DETERGENTS-soap-like compounds that remove deposits from engine surfaces. They consist of metal atom, such as Calcium, with a hydrocarbon attached to it. Simply described, the metallic "head" removes deposits and the hydrocarbon "tail" dissolves it into the oil.

detergent action

DISPERSANTS-organic compounds that contain no metallic component. They hold contaminant particles in suspension ithe oil until they are removed at oil drain.

dispersant action


detergent versus dispersant