Reduces engine friction & wear. Quiets noisy lifters & valves. Removes & prevents sludge. Keeps engine clean. Add Rislone Engine Treatment Concentrate to your oil at any time or with an oil change. Safe to use with all motor oils including conventional, high-kilometre and synthetic oils. Dissolves harmful deposits, gum and sludge without plugging oil passages. One bottle treats up to 6 litres of oil.