Increasing fuel economy and emissions standards continue to drive automotive technologies, and those technologies are placing higher loads and demands on lubricants. OEMs are demanding engine oils that assist them in meeting fuel economy and emissions requirements while protecting engines through the life of the vehicle. Idle stop, low-speed pre-ignition and turbocharged engines are just a few of the protection challenges in front of modern automotive engine oils.
The pending ILSAC GF-6 engine oil specification is intended to address the issues arising from emerging technologies. However, with timing getting pushed out to 2019 or 2020, API updated its SN rating, releasing the SN Plus oil classification as a stop gap.
Low Speed Pre-Ignition
The primary focus of API SN Plus is LSPI (low speed pre-ignition) mitigation, a run condition found in TGDI (turbocharged gasoline direct injection) engines. LSPI is a condition where combustion occurs before the timed spark, resulting in excessively high cylinder pressures which can damage pistons, bearings, and other internal engine components. LSPI can be affected by antioxidant and detergent systems used in engine oil. API SN Plus is formulated to prevent LSPI as well as limit turbo coking and deposits which can damage turbochargers.
SN Plus licensing started on May 1, 2018, and two new API donuts have been introduced to identify API SN Plus blends. Until ILSAC GF-6 is released in 2019 or 2020, manufacturers and service providers are encouraged to use API SN Plus in TGDI engine applications.