When adding oil to the crankcase or changing the oil and filter, it is important that oil of an equal quality to original equipment be used in your vehicle. The use of inferior oils may void the warranty, damage the engine, or both.
The Society of Automotive Engineers (SAE) grade number indicates the viscosity of the engine oil, and thus its ability to lubricate at a given temperature. The lower the SAE grade number, the lighter the oil. The lower the viscosity, the easier it is to crank the engine in cold weather but the less the oil will lubricate and protect the engine at high temperature. This number is marked on every oil container.
Oil viscosities should be chosen from those oils recommended for the lowest anticipated temperatures during the oil change interval.
Multi-viscosity oils (10W-30, 20W-50, etc.) offer the important advantage of being adaptable to temperature extremes. They allow easy starting at low temperatures, yet give good protection at high speeds and engine temperatures. This is a decided advantage in changeable climates or in long distance touring.
The American Petroleum Institute (API) designation indicates the classification of engine oil for use under given operating conditions. Only oils designated for use Service SE or SF or greater should be used. Oils of this type perform a variety of functions inside the engine in addition to the basic function as a lubricant. Through a balanced system of metallic detergents and polymeric dispersants, the oil prevents the formation of high 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. Both the SAE grade number and the API designation can be found on the oil container.