Oil Service Rating The oil service rating is a set of letters printed on the oil can to denote how well the oil will perform under operating conditions. The American Petroleum Institute (API) sets this performance standard.

The API system for rating oil classifies oil according to its performance characteristics. The higher rated oils contain additives that provide maximum protection against rust, wear, oil oxidation, and thickening at high temperatures. The oil service ratings are as follows:

1. SA - adequate for utility engines subjected to light loads, moderate speeds, and clean conditions. Contains no additives.

2. SB - adequate for automotive use under favorable conditions (light loads, low speeds, and moderate temperatures) with relatively short oil change intervals. Generally offers only minimal protection to the engine against bearing scuffing, corrosion, and oil oxidation.

3. SC - meets oil warranty requirements for 1964 through 1967 automotive gasoline engines.

4. SD - meets oil warranty requirements for 1968 through 1970 automotive gasoline engines. Offers additional protection over SC oils that are necessary with the introduction of emission controls.

5. SE - meets oil warranty requirements for 1972 through 1979 automotive gasoline engines. Stricter emission requirements created the need for this detergent oil.

6. SF - meets oil warranty requirements for 1980 through 1988 automotive gasoline engines. The SF oil is designed to meet the demands of small, high-revving engines. A SF oil can be used in all automotive vehicles requiring detergent oil.

7. SG - meets oil warranty requirements for 1989 through present automotive gasoline engines. Contains more additives than SF oils. Can be used as CC or diesel type oils. It is a detergent oil.

8. CA - meets all requirements for naturally aspirated diesel engines operated on low sulfur fuel.

9. CB - meets all requirements for naturally aspirated diesel engines operated on high sulfur fuel.

10. CC - meets all requirements for lightly supercharged diesel engines.

11. CD - meets all requirements for moderately supercharged diesel engines.

The operator's manual provides the service rating recommended for a specific vehicle. You can use a better service rating than recommended, but NEVER a lower service rating. A high service rating (SG, for example) can withstand higher temperatures and loads while still maintaining a lubricating film. It will have more oil additives to prevent oil oxidation, engine deposits, breakdown, foaming, and other problems.

LUBRICATING (OIL) SYSTEM COMPONENTS

It must be remembered that the lubricating system is actually an integral part of the engine and the operation of one depends upon the operation of the other. Thus the lubricating system, in actual practice, cannot be considered as a separate and independent system; it is part of the engine. The lubricating system basically consists of the following:

Oil Pan - reservoir or storage area for engine oil.

Oil Level Gauge - checks the amount of oil in the oil pan.

Oil Pump - forces oil throughout the system.

Oil Pickup and Strainers - carries oil to the pump and removes large particles.

Oil Filters - strains out impurities in the oil.

Oil Galleries - oil passages through the engine.

Oil Pressure Indicator - warns the operator of low oil pressure.

Oil Pressure Gauge - registers actual oil pressure in the engine.

Oil Temperature Regulator - controls engine oil temperature on diesel engines.

Oil Pan

The oil pan, normally made of thin sheet metal or aluminum, bolts to the bottom of the engine block. It