API Car Engine Oil Specification Explained

API Spec is a very common sight, in fact you'll find one on almost all engine oil, but what does it all mean?

API (American Petroleum Institute) specifications are often seen on oil containers and they show the minimum standard of oil that can be used in an engine. You can't really use the API specifications to measure the quality of an oil as many of the top end ester based oils meet API SL rather than the latest API SM specification

American Petroleum Institute (API) Engine Oil Specifications

S = Service - Petrol Engine Performance

C = Commercial - Diesel Engine Performance

Petrol Engine Specification

SG

Introduced 1989 has much more active dispersant to combat black sludge

SH

Introduced 1993 has same engine tests as SG, but includes phosphorus limit 0.12%, together with control of foam, volatility and shear stability

SJ

Introduced 1996 has the same engine tests as SG/SH, but phosphorus limit 0.10% together with variation on volatility limit.

SL

Introduced 2001, all new engine tests reflective of modern engine designs meeting current emissions standard

SM

Introduced November 2004, improved oxidation resistance, deposit protection and wear protection, also better low temperature performance over the life of the oil compared to previous category

Diesel Engine Specification

CD

Introduced 1955, international standard for turbo diesel engine oils for many years, uses single cylinder test engine only.

CE

Introduced 1984, improved control of oil consumption, oil thickening, piston deposits an wear, uses additional multi cylinder test engine.

CF4

Introduced 1990, further improvements in control of oil consumption and piston deposits, uses low emission test engine

CF

Introduced 1994, modernised version of CD, reverts to single cylinder low emission test engine. Intended for certain indirect injection engine

CF2

Introduced 1994, defines effective control of cylinder deposits and ring face scuffing, intended for 2 stroke diesel engine

CG4

Introduced 1994, development of CF4 giving improved control of piston deposits, wear, oxidation stability and soot entrainment. Uses low sulphur diesel fuel in engine test

CH4

Introduced 1998, development of CG4, giving further improvements in control of soot related wear and piston deposits, uses more comprehensive engine test program to include low and high sulphur fuels SG - Introduced 1989 has much more active dispersant to combat black sludge.

CI4

Introduced 2002, developed to meet 2004 emission standards, may be used where EGR (exhaust gas recirculation) systems are fitted and with fuel containing up to 0.5 % sulphur. May be used where API CD, CE, CF4, CG4 and CH4 oils are specified

Updated on: 07/01/2019