Four year old diesel
 

I’m looking at buying a fairly new motorhome, it’s a diesel pusher. It has not been started in four years. The owner is concerned that they need to drain the diesel before they start it.

This coach is the desert in California, we get pretty clean diesel out here. I never even changed the filters on my 240D in five years.

I thought diesel could stand for years and years and years without an issue.

I want to start it, but they’re putting me off.

What’s the truth on that, you guys seem to know all about diesels and helped me a lot with the 240D.

Thank you

Diesel will last a long time IF it's stored in a full tank. If there's a big volume of air above the fuel that's when you get algae growth.

Diesel will develop fungus or algae if left standing unless the fuel was treated - and that seems unlikely given your inquiry. Moisture isn't so much the issue where you are. I'd probably give it a try - the current filters will catch any problem or plug up and prevent you starting it. Also, on a motor home, draining the fuel isn't so hard.
One other thought, just get a sample of the fuel and give it the sniff test. Old fungus diesel smells bad. Not like fresh fuel.

Thank you

I'd dump in some biocide and go for it. I took heating oil from a tank in my old office building which had set for about 40 years. It was good enough to use in my buddy's earth mover.

Rig a small aux tank and patch it in bypassing the old fuel.

I'd trust a Cummins pusher. Cat's are expensive to service