Rotella is popular but it is a diesel rated oil.. that basically means that it has more aggressive additives for diesel motors.

It will work fine in a carburetor gasoline motor. I rarely see Rotella in anything other than 15W40.

Funny thing is that Rotella meets an obsolete API spec, CF/CF-2. But that is a good thing... that means it has lots of that magical ZDP that people go nuts over.

Only the 10W and 30 meet Allison C-4 spec. And lo and behold that Allison C-4 sped is dead:

"Allison C4 fluids are no longer approved for Commercial On-Highway products"
(http://www.allisontransmission.com/service/autoapp/172/viewpage.jsp?ThisPage=12

Only the synthetic Rotella oil meets any current spec.

But for an old 235... its really good stuff.