API Service Category SM was first introduced in 2004 for use in gasoline engines and is not suitable for use in engines introduced after 2010. API continues to license engine oils against API SM and it is considered to be a current specification.
Oils that satisfy API Service Category SM are superior in performance to those meeting API SL and earlier and can effectively lubricate engines calling for those Service Categories.
Due to newer API Service Categories (API SN PLUS and API SN) being suitable for use in applications specifying API SM many oils available today also claim to meet the requirements of API SM. This leads to API SM being seen to a wide range of lubricants of different performance levels and viscosity grades.
Where only API SM is claimed these oils are typically high HTHS (≥ 3.5cP) SAE 10W-40, 15W-40 and 20W-50 based on API Group I or Group II base oils.
In some cases oils meeting API SM also carry an Energy Conserving claim to show that the oil has been formulated to improve fuel efficiency. These oils are typically low HTHS (≤ 3.5cP) SAE 5W-30 and 5W-20 based on API Group II base oils and coupled with ILSAC GF-4.
For more information on API SM, contact your Lubrizol representative.