any thoughts?

family friend swears by them.

As long at the oil meets or exceeds the minimum requirement of the device... Why not. The only other factor will be is cost.

Never heard of it.

If it's CI-4 and not CJ-4 I would be all over it. Personal experience showed me the CI-4 is better oil.

I have never heard of them either. 

http://swepcolube.com/

 

http://swepcolube.com/products/swepco-308-premium-cj-4-plus-diesel-engine-oil
 

Been around awhile...

 

Southwestern Petroleum Company, Inc. was founded in 1933 in Fort Worth, Texas

 

I'm more interested in the 306 engine oil and the 212 gear lube.

But if no one has used them, going off a 96 year old mans word might be enough, he has 40 gal of the 306, and a gal of 212. I can get on the cheep from him.

Thanks again.