Oils and lubricants are classified and graded according to standards established by the Society of Automobile Engineers (SAE), American Petroleum Institute (API) and the National Lubricating Grease Institute (NLGI). Engine oils are classified by the SAE and API designations found on the top of the oil can. The SAE grade number indicates the viscosity of engine oil. SAE 10W-40, for example, is a good all-temperature motor oil suitable for use in winter.The API classifications system defines oil performance in terms of usage. For gasoline engine Volvos, only oils designated SE or SF should be used. These oils provide sufficient additives to give maximum engine protection over a wide range of operating conditions.
Oils of the SE or SF variety performs a multitude of functions in addition to their basic task of lubricating. Through a balanced formula of metallic detergents and polymeric dispersants, the oil prevents high-temperature and low-temperature deposits and also keeps sludge and dirt particles in suspension. Acids, particularly sulfuric acid, as well as other by-products of combustion, are neutralized by the oil. These acids, if permitted to concentrate, may cause corrosion and rapid wear of the internal parts of the engine.
Volvo diesels must use SE/CC or SF/CC motor oils. Those built in 1984 and later require oil designated CD. Note that the letters CD or CF appear in addition to all the other designations on the can. A sample designation might read: SAE 15W/40 SF/CD. This indicates that the oil provides protection from rust, corrosion and high temperature deposits in diesel engines used in moderate to severe service. Use the accompanying oil temperature range charts to select the correct SAE weight motor oil for the climate in which you will be driving.
See FIgures 1 and 2