By adding BIZOL Pro Oil System Clean+ p91 before changing the engine oil, residues not soluble in oil are dissolved by the highly-effective detergent additives and flushed out together with the oil change. It has been proven that such cleaning can correct loss of compression and very possibly enable the engine to regain its optimum performance. Furthermore, clean oil ducts allow for fast circulation of oil through the engine especially on cold-starting, which in turn reduces the wear on engine components and also reduces fuel consumption while leading to improved exhaust emission values.