Throttle Muscle Engine Scrub is a super concentrated premium crankcase cleaner. While some engine flushes are only a solvent, Throttle Muscle Engine Scrub also contains a special residue solubilizer and a high quality engine oil base. To perform a complete engine flush, simply add our 128 Oz bottle of Engine Scrub and a new oil filter. Allow engine to run five minutes at idle (do not rev). Drain Engine Scrub and replace with fresh oil, also replace the oil filter with a brand new filter. Check to verify that all your fluids are full and you are ready to go.