Flushing oil is a low viscosity oil that is used to remove harmful deposits and sludge from engines. Help keep your vehicle in optimum condition by using engine flushing oil. This is a very thin product made specifically to seek out, attract and collect all the gunk that can build up in an engine over time. If you decide to do an engine oil flush then it's worth putting in a clean oil filter before you do so, to trap all the dirt that is collected by the flushing oil. Using a quality flushing oil will result in a cleaner engine and will minimise the chances of getting sludge build up.