Lubricants designed for medium-speed 4-stroke marine engines using HFO heavy fuels with a high sulphur content (up to 3.5%). Developed with a new technology that gives an outstanding performance against thermal degradation and oxidation. The excellent detergent and dispersant additive system promotes piston cleanliness and a very good control of fuel contaminants. This results in providing an excellent oil-fuel compatibility, high base number retention, extreme reduction of deposits, better protection against the corrosion caused by acids and a much longer service life.