The service rating of motor oils is classified by the American Petroleum Institute (API). The program certifies that an oil meets certain OEM quality and performance standards. The service rating is shown in the API "Service Symbol Donut" on the product label. There may also be an "API Certified for Gasoline Engines" seal on the label.
The latest service category rating for gasoline engines is "SM", introduced in November 2004 for 2005 and newer engines. SM-rated oils along with the previous "SL" (2001) and "SJ" (1997) ratings, are backwards compatible and can be safely used in older engines. But the opposite is not true. Older obsolete service classifications (SH, SG, SF, etc.) may not meet OEM lubrication requirements for newer engines. Likewise, API SL oils should not be used in 2005 and later vehicles, and SJ oils should not be used in 2001 and newer vehicles.
To view the current API rating system, click here..
For diesel engines, API has a separate rating system. The current category is "CI-4" (introduced in 2002 for newer diesels that have exhaust gas recirculation). The previous CH-4 (1998), CG-4 (1995), and CF-4 (1990), can all be used in older four-stroke diesel engines. CF-2 (1994) is the API classification for two-stroke diesels.
API also gives oils an "Energy Conserving" rating if the oil meets certain criteria for reducing friction and oil consumption, and improving fuel economy.
Motor oils that meet the current API SM rating may also meet the new International Lubricant Standardization and Approval Committee (ILSAC) "GF-4" specifications, which some European and Asian auto makers require.
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New GF-5 Moil Oil Specification Coming The new GF-5 motor oil specification, created by the International Lubricant Standardization and Approval Committee (ILSAC), is scheduled to take effect in the summer of 2009 and will be the factory fill for 2010 model-year engines. GF-5 motor oils will be the most technologically advanced motor oil, exceeding the current GF-4 category in a number of important performance areas. ILSAC identified several major areas that automakers would like to see improved with the GF-5 category. These areas include: fuel economy and fuel economy retention throughout the oil drain; emission-control systems protection; and increased sludge, deposit and oxidation control. In addition, ILSAC identified a number of other areas to be addressed by the GF-5 specification, among these include low-temperature viscosity, high- and low-temperature corrosion, turbocharger protection and filter clogging protection. Aeration control, the reduction of tiny air bubbles, is a renewed concern because modern engines demand that oil serve as a hydraulic fluid in cam phaser devices, variable valve actuators, timing chain tensioners and hydraulic lash adjusters that allow for variable valve timing. These increased demands cause engine oils to be stressed more than ever before. One of the highest priorities for automakers and engine oil manufacturers is making GF-5 motor oil backward compatible. Developing engine oil that is compatible for new and older engines helps prevent misapplications. |
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