8 Questions Answered: API SN PLUS Motor Oil Specification

Yes, Quaker State products that meet the API SN PLUS specification have the new API Donut designation on the bottle beginning May 1, 2018.

• The API SN PLUS motor oil specification is intended to complement API SN and ILSAC GF-5 and aimed at addressing the increasing impact of Low-Speed Pre-Ignition in Turbocharged Gasoline Direct Injection (TGDI) engines.
• The high pressures from turbocharging combined with direct fuel injection into the combustion chamber in these smaller TGDI engines makes them susceptible to a phenomenon known as Low Speed Pre-Ignition, or LSPI. While the mechanism of LSPI is not yet fully understood, research has shown that motor oil properties may be a contributing factor. Automakers can mitigate LSPI by adjusting the engine operating conditions, but in doing so inhibit some high efficiency engine operating conditions.
• Amid growing concerns about LSPI among Automakers, the urgent need for a supplemental motor oil specification became evident. This new supplemental specification, known as API SN PLUS, includes the testing protocol for API SN and a special test for LSPI, the API Sequence IX test.
  
  

• Low-Speed Pre-Ignition (LSPI) is an abnormal combustion phenomenon observed at low engine speeds in which the fuel/air mixture in the combustion chambers ignites before spark timing. LSPI can cause engine knock, broken spark plugs and cracked pistons, and, in severe cases, catastrophic engine failure.
• There are multiple theories about what causes LSPI in downsized TGDI engines, although it is widely accepted that motor oils can play a role. Research has shown that during LSPI a drop of oil in the cylinder may be combining with fuel droplets to create hots spots in the combustion chamber and prompting ignition before spark timing is intended to occur. Research has also shown that motor oils can be re-formulated to significantly reduce their contribution to LSPI, which is the goal of the new API SN PLUS supplemental motor oil specification.
• GM chose to address LSPI with the introduction of its dexos1™ Gen 2 specification, which went into effect on September 1, 2017.
  

The Auto-Oil Advisory Panel, which is developing the standard, has commissioned a new testing method for LSPI. This test is based on a Ford engine and is designated the API Sequence IX test. LSPI performance is also tested in the General Motors-specific LSPI test that is part of their dexos1™ Gen 2 testing protocol.

To find out if your vehicle has a turbocharged engine and requires an API SN PLUS motor oil, we recommend checking your vehicles owner’s manual. While not all engines need additional protection against LSPI, all Quaker State products meeting API SN PLUS also meet or exceed all API SN standards.