PETROMARK® 10123 Hydraulic Valve Lifter is a very special oil additive which dampens the noise produced by worn hydraulic valve. It cleans the valves and oil ways in the hydraulic tappet and promotes optimum operation. Suitable for max. 6 litres motor oil. Add the entire contents of the 250 ml. bottle to the oil when engine is at operating temperature. This PETROMARK® product can be mixed with all types of motor oil. Suitable for all petrol, diesel and LPG engines.