North American Gasoline Motor Oil Specifications

Tech Talk Uncategorized


Amsoil Vice President of Technical Development

With three major specifications now in play shows they continue to evolve, consumers are facing an increasingly complex market.

The automobile industry is continually changing; between advancing technologies and increasingly stringent performance mandates, change is constant and essential. In North America, engine oil specifications have traditionally been governed by the American Petroleum Institute (API) and the International Lubricant Specifications and Approval Committee (ILSAC).

The API first created engine oil groups in 1947 and has been continually improving engine oil specifications ever since. The API represents the interests of hundreds of oil marketers and defines oil service categories in addition to administering the Engine Oil Licensing and Certification System (EOLCS). There are currently two registered marks administered by the EOLCS: the API service symbol (donut) and the ILSAC certification mark (starburst). Certified oils carry one or both of the registered marks. Since the development of the “S” and “C” categories around 1969/1970, the API, the American Society for Testing and Materials (ASTM) and the Society of Automotive Engineers (SAE) have been working together to develop engine oils that meet changing performance demands.

New GL-5 Oil Specifications
This diagram outlines the different areas of improved performance emphasized by GF-5 and dexos1. While each specification outperforms the other in certain areas, AMSOIL has formulated its oils to the highest standard of both specifications in all areas.

In 1987, the Alliance of Automobile Manufacturers (AAM, formerly AAMA) informed the API that it was dissatisfied with the current approach for approval of motor oils and created a new system for approval governed by a new committee, ILSAC. ILSAC consists of nine original equipment manufacturers (OEMs) from North America, Europe and Japan. ILSAC recently developed the GF-5 oil standard, which improves performance over the previous standard, GF-4. The increased performance standards are achieved by mandating certain performance requirements; some of the main improvements have been aimed at fuel economy, engine oil robustness and emissions system protection.

The API’s most recent service categories are SN and SN “Resource Conserving.” The API SN category applies to oils for gasoline-powered passenger cars, SUVs, vans and light-duty trucks. The API SN Resource Conserving category requires increased performance over SN and more closely matches the ILSAC GF-5 specifi- cation. The API SN and SN Resource Conserving licenses were both introduced October 1, 2010.

General Motors complicated matters a bit this year with the introduction of its dexos1™ oil licensing program. GM created the dexos1 oil specification to reduce the oil’s impact on the environment and increase its performance in certain categories. dexos1 has tighter performance requirements than GF-5/API SN in some areas and looser requirements in other areas. Consumers driving model-year 2011 and newer GM vehicles will have to be sure they use an oil recommended for dexos1 applications.

Government mandates weigh heavily in the formulation of motor oils and the development of new service categories. Federal regulations for automotive performance, fuel economy and emissions limits are becoming increasingly stringent, requiring vehicle manufacturers and oil companies to develop technologies to meet these requirements.

Vehicle manufacturers are developing new engines and emissions systems that meet the requirements, but they are also relying on oil manufacturers to help meet the new mandates. Governmentmandated corporate average fuel economy (CAFE) requirements are focused on improving the average fuel economy of vehicle manufacturers’ passenger car and light-truck fleets. The National Highway Traffic Safety Administration (NHTSA), together with the Environmental Protection Agency (EPA), monitors the fuel economy and emissions performance of vehicles. The average fuel economy of an OEM’s fleet of vehicles must meet the minimum CAFE standards or OEMs face costly penalties.

With all these changes happening at the same time, it can be difficult to sort out all the updates and differences between specifications. AMSOIL simplified the situation for Dealers and customers by formulating motor oils that meet or exceed performance standards in each of the main categories. AMSOIL OE and XL Synthetic Motor Oils meet the API SN Resource Conserving and ILSAC GF-5 performance requirements; OE 5W-30 and XL 5W-30 meet the GM dexos1 performance requirement. The top-tier line of AMSOIL synthetic motor oils will be reformulated to meet the latest industry specifications in the first quarter of 2011.


I have been selling and using Amsoil products since 2008. I will not sell any product I don't use myself. Your cars will last for 150K+ miles with no problems. I have a 2004 Toyota truck with 217K miles and a 4runner with over 170K miles running fine. Cell: (702) 994-4646

Leave a Reply

Your email address will not be published. Required fields are marked *