What fuel are you running?

[cllctrtom]

What kind of fuel, (or additive) are people running in their MUTTS? I just bought one with 126 miles on it. 1977 production. What do you suggest?

[halftracknut]

Wow, I would love to see a picture of your jeep...I use unleaded high test with " Sta-Bil" fuel preservative ... or regular unleaded with NO corn oil in it...

[Rainman]

I don't have a mutt, I have an M151A2 jeep and I run regular unleaded w/ a slosh of Marvel Mystery Oil mixed in.

It should also be noted that many later M151A2's were mfg'd to be operated with unleaded fuels and many others retrofitted with the unleaded head with hardened valves. Mine is a retrofit.
Rainman

[SEABEE62]

I have a MUTT....and White lighting works Seabee

[Rainman]

Exactly my point hammer man! Thanks for that confirmation.
Rainman

[rickf]

With the massively high compression of 7:1 you will get the most power out of regular gasoline. Premium burns slower to prevent pre-ignition in high compression engines.

[mallard]

I've been running 87 no ethanol with some sea foam mixed in

[raymond]

I've run plain old 87 octane regular unleaded in mine since 1997.

[whiterabbit]

I get the cheapest "gas" I can get and a splash of Staybil ethanol treatment. I think the treatment is helping prevent the white deposits but that corn piss is eating the accelerator pump in the carb and I know it's doing the same to the fuel pump. I just swapped out to the Dodge pump to prevent being dead along side the road on some upcoming road trips.
I might swap out to Marvel Mystery Oil.
Military engines are designed to run on any crappy fuel from any crappy country we happen to be in.

[rickf]

Older military engines were designed for that, not these. The M-151 was a product of the budget cutters and as a result it was the cheapest and crappiest thing they could get for the money. It was designed to do the job for a short amount of time and then be thrown out. Nobody ever planned on them being in service for even half as long as they were. The carburetor on these things is so sensitive to even the slightest stale gas I can't believe it was in a military vehicle. Luckily by the time it was in use we pretty much had the logistics to keep our own supplies of fresh fuel on hand.

[Lindsay36551]

How can you tell if you have the retro heads?
Do you need to tear it down?
Noticed mine has a puff of gray smoke on a cold start!

[rickf]

Valve seals are going bad. New style heads have larger bosses where the exhaust manifold bolts go.

[Cobra5]

100LL but my jeep does more sitting than driving. I'm going to switch out to 92 Octane because its the only fuel here that doesn't have Ethanol. Of course I'll have to start driving it more. At the end of the season I'll drain my tank and run 100Ll through it to keep the carb preserved.

[cllctrtom]

I don't have a mutt, I have an M151A2 jeep and I run regular unleaded w/ a slosh of Marvel Mystery Oil mixed in.

It should also be noted that many later M151A2's were mfg'd to be operated with unleaded fuels and many others retrofitted with the unleaded head with hardened valves. Mine is a retrofit.
Rainman

How can I tell if mine is made that way or retrofitted?

Thanks!

[cllctrtom]

Thanks to everyone for your replies. It will help me keep my Jeep running right!