Lube basics

Motor,  Nov 2002  by Layne, Ken

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Diesel oils CA through CE were in use from the 1940s through the 1980s but are obsolete today. CD-II oils were developed to meet all the performance requirements of CD oil, but for two-stroke diesels. CD-II, in turn, was superseded in 1994 by CF-2.

CE oil was introduced in 1983 for four-stroke supercharged and turbocharged diesel engines and can be substituted for CC and CD oils. CF oil was introduced in 1994 for improved protection of engines using high-sulfur fuels.

CF-4, CG-4, CH-4 and CI-4 are designed for high-speed, four-stroke diesels. CI-4 was introduced in December 2001 and can be substituted for previous service classifications that end in "-4."

Multiple Service Classification

Most oil companies sell oils with multiple service classifications, such as CI-4/SL or CH-4/SJ. This means that the oil meets the requirements of all service classifications listed in the rating and is suitable for different engines operating under varying conditions. Some vehicle manufacturers are very specific about service classification recommendations, particularly for supercharged, turbocharged and diesel engines. If a manufacturer specifies an oil with a dual service classification, do not use oil that meets only a single classification.

To provide uniform identification and all consumer information in one place, the API created the API service symbol. The symbol is shaped like a doughnut and contains the service classification and the viscosity grades. The words "energy conserving" also may be at the bottom of the symbol if the oil meets the requirements. This symbol can be used on an oil container only with licensing approval of the API.

Recent Service Classifications & Viscosity Requirements

Competitive market forces and government regulations for fuel economy and emissions control are the major forces that have driven recent advances in motor oil. Besides the service classifications and viscosity grades, some oils for the past 10 or 12 years have been designated as "energy conserving" or "energy conserving II" by the API. These oils are formulated to reduce engine friction and thus improve fuel economy by 1.5% or 2.7%, respectively. Energy-conserving oils have more friction-reducing additives and relatively low viscosities.

Since 1993, oil quality also can be identified by the API certification mark, or "starburst" symbol. This symbol indicates that the oil has been certified by the International Lubricant Standardization & Approval Committee (ILSAC) as the correct type of oil for gasoline engines in passenger cars and light trucks. To qualify for the starburst symbol, oils must meet the energy conserving II requirements. Therefore, only multiviscosity oils with SAE 0W, 5W and 10W ratings-such as 0W-20, 5W-30 or 10W-30-will qualify.

Oils that qualify for the starburst symbol may also carry ILSAC classification GF-1, GF-2 or GF-3, which indicates the energy-conserving qualities. GF-3 was introduced in late 2001 and claims a .5% fuel economy improvement, a 40% reduction in oil consumption, a 25% increase in oil life, better oxidation stability and protection against high-temperature deposits. If an oil container has an API starburst symbol and SL in the doughnut symbol, the oil meets GF-3 requirements.