A Primer on the API SP and ILSAC GF-6 Engine Oil Standards

  • Post published:March 25, 2021

A Primer on the API SP and ILSAC GF-6 Engine Oil Standards

As your premier provider of fuel and lubricant solutions in the Pacific Northwest, Christensen is dedicated to helping your business meet the latest oil specifications and standards. Emission and fuel economy regulations are becoming more stringent due to a combination of factors including consumer demand and the realities of climate change, energy security, and air pollution. One of the key goals is to meet a 54.5 mpg and 165mg CO2/mile requirement by 2025. As such, the American Petroleum Institute (API) approved the new API SP and ILSAC GF-6 oil specs. In this article, we will give a rundown on GF-6 ILSAC standard.

GF-6 Explained

This is the latest International Lubricants Specification Advisory Committee (ILSAC) standard for passenger car motor oils. The reasons for its ratification include the greater demand for fuel economy and the reduction in CO2 emissions. Due to this, automakers have been downsizing engines and introducing Turbocharged Gasoline Direct Injection (TGDI) engines, which in turn require better protection against Low-Speed Piston Pre-Ignition issues and timing chain wear.

GF-6 will be split into two sub-categories. This is similar to the current API specifications for heavy-duty engine oils – CK-4 and FA-4. The GF-6 subcategories are:


A backwards compatible standard for SAE 0W-20, SAE 5W-20, SAE 0W-30, SAE 5W-30, and SAE 10W-30, but not SAE 0W-16. This standard will continue to utilize the starburst symbol for licensing


The new standard for SAE 0W-16 only, devised to meet the needs of certain modern engines. This standard is not backward compatible with previous categories and has a new licensing symbol.

Why is the New ILSAC Standard Needed by the Industry?

Original Equipment Manufacturers (OEMs) continue to push for increased fuel economy and compliance with emission standards. So new ILSAC standards are needed to meet the requirements necessitated by these advancements.

As previously explained, to increase fuel economy many OEMs are utilizing TGDI engines. As these are susceptible to Low Speed Pre-Ignition, motor oils must be designed to address this issue. The ILSAC GF-6 addresses LSPI, improvements in protecting against sludge and varnish, as well as protections against turbo deposits and timing chain wear.

ILSAC standards are made with backwards-compatibility considerations so that new standards still meet the need of prior engine technologies. Because the new SAE 0W-16 viscosity grade has not been specified for most older engines, as most are not equipped to operate lubricants at such low viscosity, ILSAC implemented the GF-6A standard.

GF-6A is backwards compatible while the GF-6B standard is used only for SAE 0W-16. So oils meeting the latter standard will not be backwards compatible unless specified as such by an OEM. This distinction will be noted visibly on appropriate Christensen oil labels.

ILSAC GF-6 Does Not Replace the API SN PLUS Service Category

ILSAC standards and API service categories are separate but interrelated. The motor oil and automotive industries collaborate to define new ILSAC standards. Once the standar is approved by both authorities, API handles licensing of the ILSAC starburst – a registered mark clearly identifying passenger car engine oils meeting the latest ILSAC performance standard.

API SN PLUS was a supplemental service category adopted by the API to provide consumers with motor oils that reduced the occurrence of LSPI in TGDI engines while the ILSAC GF-6 was being developed.

API’s “SP” service category is derived from ILSAC GF-6 and licensed to motor oils for gasoline engines. Though API SP is backwards compatible to previous API service categories, motor oils can still be licensed to meet the API SN PLUS, SN, SM, SL or SJ categories. API allows licensed motor oils to display the API “donut” indicating which API service category it meets.

What is LSPI?

Low-Speed Pre-Ignition is a combustion phenomenon that typically occurs when engines are operating at low speeds and high loads. The fuel-air mixture in the combustion chambers ignites before spark timing and can cause engine knock and even catastrophic engine failure in severe cases.

While there are multiple theories as to the causes of LSPI, it is widely accepted that motor oils can play a role. Suspected causes include:

– A drop of oil in the cylinder combines with fuel droplets to create hot spots in the combustion chamber and causes ignition before spark timing as designed.

– Carbonaceous deposits in the combustion chamber made of hot particles released from the piston land or crown

– Fuel spray on cylinder walls

According to research, motor oils can be reformulated to significantly reduce the likelihood of LSPI. This was the goal of API SN PLUS, a supplemental service category introduced in 2018. The new ILSAC GF-6 standard was made to address LSPI in downsized TGDI engines and protect newer engine technologies.


The advances in OEM designs aimed at meeting the latest emission and fuel economy requirements necessitates matching oil standards. And as a leading supplier of fuels, lubricants and propane products, Christensen is here to provide businesses with oils meeting these latest standards so that they, in turn, can meet their customers’ requirements.