Quote Originally Posted by Boatsb View Post
A post from Bobk way back when


Low ash (<1.0%) is preferred for the two stroke engines. Detroit has a PDF on this but I could not find it. Remember, two strokes need straight 40 oil.

This information is a bit old, but may be good. Shell Rotella 40 is at the upper limit of the ash spec. I've used it, but switched to NAPA 75118 (Valvoline) as it is well below the spec and I can easily get it anywhere.
ASH, %

Exxon XD3____________.80%
Mobil Delvac 1240______.80% (if you can still find it)
Castrol Assuron________.80%
Valvoline Fleet Plus_____.80%
Delo 100______________.85%
Texaco Ursa___________.85%
Shell Rotella__________1.00%
Valvoline Fleet Guard Plus SAE 40 also meets the 0.8% spec

Funny how these things get attributed to others. I compiled that list and posted it that years ago. At the time I was using the XD3, thats why it was on the top of the list. Some of those oils are no longer available.