I'm thinking of buy a 1986 F350 4x4 Crewcab 460 that has a dual use gas/propane system. It's got 140,000 miles. I did a search but couldn't find much on 460s and propane. Some said that propane is clean and the engine will last longer. Some said that propane doesn't lubricate and causes the valves to fail early. Anyone have thoughts on these? Are they a headache or do they work well? Is it more economical to use propane than gas? Anything specific to look at? I tried to check the oil but it didn't touch the stick.

Any wisdom to pass along when I'm looking at this truck?

 

That there alone would make me want to stay away from that truck.