Will AMSOIL 5W-40 for 229.51 harm engine?
My understanding is that MB originally said that 229.51 ("low SPAsh") oil was fine for both diesel and gas, however, they have since removed the approval for use in gas engines in the US due to concerns over the quality of our gasoline (and perhaps the ethanol content). I believe 229.51 is still allowed in gas engines in some countries, but I could be wrong. The difference between 229.5 and 229.51 is that the 229.51 has less of certain additives (ash) to protect the exhaust emissions equipment in newer (2007+) diesels.
Despite the lack of official MB approval, I seriously doubt it will cause any problems in the span of one oil change, but if it were me, I would probably reduce the oil change interval a bit this time, rather than going the full 1 yr/10k miles.
I put diesel oil in mine, Shell Rotella T6 5w40. People put it in their 911's.
Enjoy!


