Do turbocharged DI engines now require SN Plus oil?
Thread Starter
Junior Member
Joined: Sep 2010
Posts: 64
Likes: 6
2013 S550 4Matic
Do turbocharged DI engines now require SN Plus oil?
I understand that there is a new, poorly understood low speed pre-ignition (LSPI) phenomenon happening with turbocharged direct injection engines such as the one in our 2013 S550. The problem seems widespread and there is now a new oil classification API SN Plus to help address this problem. Has the oil recommendation for the 2013 and later S550 changed? I searched but did not find any discussion of this?
The current theory is that oil droplets get thrown from the piston rings under high load but low RPMs causing pre-ignition which can be destructive to engines. Reformulation of the engine oil can help address this. Thus the new API SN Plus formulation.
The current theory is that oil droplets get thrown from the piston rings under high load but low RPMs causing pre-ignition which can be destructive to engines. Reformulation of the engine oil can help address this. Thus the new API SN Plus formulation.
Last edited by gsholz; Dec 7, 2019 at 06:31 PM.
