Recommended Oil: Why Following the Manufacturer’s Guidance Is Important
Today’s new cars are sophisticated pieces of machinery made from thousands of parts. One of the key components is the engine, which is designed to optimize performance, maximize efficiency, minimize exhaust emissions and last for years. Key to an engine’s health is the type of oil used, which means using automaker recommended oil is critical in protecting your car.
Setting the Standard
There are several standards that are important when selecting motor oils: Society of Automotive Engineers (SAE) viscosity grade, American Petroleum Institute (API) service category, International Lubricant Standardization and Approval Committee (ILSAC) standards and Association des Constructeurs Européens d’Automobile (ACEA).
SAE viscosity grade refers to how well an oil flows at various temperatures. Modern engines built with very tight tolerances usually call for “thin” oils that flow easily when cold, but maintain their viscosity when hot. A typical viscosity rating in late-model engines is 0W-20.
API service categories involve a number of different tests that measure an oil’s ability to lubricate, clean, cool and protect internal engine components. Different categories apply to spark- and compression-ignition engines. SN is the latest category for gasoline powerplants, while CH-4, CI-4 and CJ-4 are all current (but not interchangeable) for diesels.
ILSAC standards parallel API categories to a degree, but include an enhanced emphasis on fuel efficiency benefits. The latest ILSAC standard is GF-5 which, in conjunction with API’s SN category, indicates oils that meet the gasoline-engine requirements of most major automakers.
ACEA sequences are a series of standards for European cars that some consider more stringent than API and ILSAC requirements. Current ACEA sequences include C for catalyst-equipped gasoline and light-duty diesel engines, and E for heavy-duty diesels.
In addition to the industry standards described above, almost every vehicle- and engine-manufacturer has unique oil specifications that involve proprietary tests to ensure oils meet the specific requirements of their powerplants. These standards are listed in your owner’s manual, and only oils that meet those requirements (in addition to SAE, API, ILSAC and ACEA standards) should be used in the vehicle.
For example, General Motors — manufacturer of Cadillac, Buick, GMC and Chevrolet vehicles — requires that 2011 and newer model year vehicles use oils that meet dexos1TM (gasoline) or dexos2TM (diesel) specifications that were developed by GM to help meet government-mandated emissions and fuel economy standards. If you have your oil changed at the dealer, they’ll probably recommend AC Delco oil, a GM-owned brand. However, there are other semi- and full-synthetic oils that also meet dexos standards.
Other examples of unique oil requirements include heavy-duty diesels in pickup trucks that usually require oils that meet certain engine-manufacturer specifications. Similarly, European automakers such as Audi, BMW, Mercedes-Benz and Volkswagen all have specific oil requirements that apply to vehicles sold in North America as well.
Your Manufacturer Warranty
All of the standards discussed above are updated periodically to keep pace with changes in engine technology. Today, most new cars require semi- or full-synthetic oils to meet all of the requirements. Using an oil that fails to meet an automaker’s specifications can result in engine wear or damage that will not be covered by the new-car warranty.
That does not mean you need to use an oil sold by the vehicle manufacturer. But, it does mean you are responsible for making sure any oil put into your engine complies with the automaker’s requirements as set forth in your owner’s manual. In most cases there are many brands of oils that will work just fine, but you need to make sure any proprietary specifications are listed on the oil container. To help motorists, some automakers such as Audi provide a list of acceptable oil formulations in their service literature.
Photo courtesy of Wikimedia Commons.