Originally Posted by Ken Blythen
TallPaul
It's an 82 - the truck has been to the moon & back, but I don't know the engine year - it's not original to the truck.
The engine (and all the running gear) has done low miles since it's last rebuild.
I missed mentioning that it is LPG dedicated, so is operating at higher temps.
In view of this, I'm leaning toward a compromise of a 15w/50
Seems I have heard that LPG is very clean burning, so one would expect that you are not going to contaminate the oil like you do with a gasoline engine. That would allow for longer OCIs. Now if you need something to take the heat better, well you can't bead an oil like Redline, which has ester base oil of the type that is the only base oil that can withstand the heat of a jet turbine. Redline is about $9 a quart though, so you would want to run long OCI. I'd call Redlineoil.com and ask them for advice on this application.
Other than that, any synthetic would likely be a good move if it runs hotter than a regular gasoline engine.