Of Mobil Delvac 1300 15W40 (conventional)....should I use it in my 900ss dry clutch motor or reserve it for my beater cars? I read that huge All About Oil thread and the results are inconclusive.
The older models were spec'ed using non synthetic oils, so of course they can use them.
1300 is not JASO MA, but that is mainly for the wet clutch.
15w40 is in the range for the carbed 900 engine. Try it and see how the tranny behaves.
My only concern is the EP capability in the tranny.
I don't think you'll be able to tell...right away.