Found this on the net.
The SL, SJ ratings denote the oil's performance rating for gasoline engines. The SL is newest and most recent standard, so oils that meet the SL standard also will meet all standards that came before it. (Not all oils have transitioned over to SL yet -- you will still find SJ, which is still fine for all current year engines.) Sometimes oil containers will include more than one "S" rating, such as the SL, SJ. This is simply for consumer convenience in identifying the correct oil, as oil meeting the SL standard also satisfies the earlier ones. So even if your owner's manual calls for SG or SH, you are still safe using SJ or SL today.