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SN oil required in new cars

by David Zatz on

Several automakers, including Chrysler, are starting to require SN-rated oils in some of their engines. The new grade is designed for better gas mileage, increased lubrication, protection for turbocharged and ethanol fueled engines, and cleaner burning; the European version is titled GF-5 and requires more testing for certification.

SN and GF-5 rated oils have measures to prevent phosphorus and sulfur from getting into the exhaust, to extend catalytic converter life.

GM’s specific version of the oil, Dexos1, passes SN tests, and extra anti-sludge, anti-foaming, and gas-mileage tests; all Dexos1 oils are synthetics. Some existing oils are able to pass Dexos1 testing. A Dexos2 oil for diesels was also unveiled this year.

General Motors does not have an oil change schedule for Dexos1, instead relying on the oil monitoring system in their cars, which can extend changes well beyond prior extended intervals. Most customers should find they are changing oil far less frequently, according to past GM releases, even without the newer oils.

Chrysler was reportedly instrumental in the creation of a 10W30 weight SN-rated oil. Other grades are to be 0W-20, 0W-30, 5W-20, and 5W-30. Most 2012 model year cars from all manufacturers are expected to use SN rated oils; the replacement cost is expected to be 10% higher, but due to the more highly refined base, the oil should last longer in normal use and result in less engine wear. GM owners, with their monitoring system, should be able to spend less overall due to wider spaced change intervals; other automakers are likely to increase their scheduled intervals as well, but customers must know that 3,000-mile changes are no longer needed in most cases to benefit.

Oils have been passing increasingly strenuous testing since the first American Petroleum Institute certifications were created. As with most new formulations, SN and GF-5 are backwards compatible (according to industry representatives), though those with some classic cars may need to consider zinc replacement additives.

David Zatz founded Allpar in 1998 (based on a site he had begun in 1993-94), after years of writing reviews for retail trades. He has been quoted by the New York Times, the Daily Telegraph, the Detroit News, and USA Today. Before making Allpar a full-time career, he was a consultant in organizational psychology. You can reach him by using our contact form (much preferred) or by calling (313) 766-2304


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