API Service Category SL was first introduced in 2001 for use in gasoline engines and is not suitable for use in engines introduced after 2004. API continues to license engine oils against API SL and it is considered to be a current specification.
Oils that satisfy API Service Category SL are superior in performance to those meeting API SJ and earlier and can effectively lubricate engines calling for those Service Categories.
Due to newer API Service Categories (API SN PLUS, API SN, API SM) being suitable for use in applications specifying API SL many oils available today also claim to meet the requirements of API SL. This leads to API SL being seen to a wide range of lubricants of different performance levels and viscosity grades.
Where only API SL 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 SL 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-3.
For more information on API SL, contact your Lubrizol representative.