American Petroleum Institute. The primary oil and natural gas trade association in the United States. API operates a voluntary licensing and certification program that allows engine oil marketers to use the API Engine Oil Quality Marks if their products meet specific requirements. CG-4 was introduced in 1995 for severe duty, high-speed, four-stroke diesel engines used in both on-highway (0.05% wt sulfur fuel) and off-highway (less than 0.5% wt sulfur fuel) applications.
API CG-4 oils are required for engines meeting 1994 emission standards. These oils provide effective control of high-temperature piston deposits, wear, corrosion, foaming, A reaction occurring when oxygen attacks petroleum fluids. Oxidation is accelerated by heat, light, metal catalysts, and the presence of water, acids, or solid contaminants. Oxidation leads to increased viscosity and deposit formation. stability and soot accumulation.
API discontinued licensing diesel engine oils against Service Category CG-4 on August 31, 2009.
For more information on API CG-4, contact your Lubrizol representative.