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Marvel Mystery Oil

Old 07-20-2002, 09:14 AM
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I use it to fog the engine in the fall because it is cheap compared to the so called "fogging oils". A cup is all that is needed for a BBC.
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Old 07-20-2002, 09:52 AM
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I have heard people use it to break in a motor. Don't know about a marine motor. Also as a "flush" to clean internals. Drain motor, fill with Mystery oil, run motor, drain, and refill with regular oil.
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Old 07-20-2002, 10:18 AM
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I've used Marvel to "fog" motors down for years !!! It's not just something you should do before the fall. Boats unless you a lucky enough to use them every day have much more corrosion inside the engines from the mosture in the air. A small amount of Marvel down the carb before you shut off, and put it away will give you a lot better longevity !!!
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Old 07-20-2002, 11:57 AM
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When I had my 82 FLH ( shovel Head ) I would mix a little in my gas tank.

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Old 07-20-2002, 12:19 PM
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We use it on motors that are not going to be run for awhile. It keeps the valves, and cylinders lubricated. Also prevents rust spots.
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Old 07-20-2002, 08:38 PM
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OK..I got a 66 stang with a 289 it sits 99.9% of its life so I can mix it with the oil to keep it fresh??? would that be right??
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Old 07-21-2002, 11:43 AM
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I've started mixing it in with the av-gas I run.
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Old 07-21-2002, 11:55 AM
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When we fog a motor, we start the engine,bring the rpm's up a little,then slowly pour the Marvel Mystery oil in the carb untill you can see smoke comming out the exhaust. Then imediatley shut the engine off.
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Old 07-21-2002, 01:29 PM
Tejas Raz
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I have used Marvel Mystery Oil for years. It's great in air tools to keep the condensation from creating rust for one thing. Chigaco Pneumatics calls out MMO by name as the recommended lube for their air tools.

Put it in the gas at around 4oz per 10 gal. for top cylinder lube. Might be just the thing for blower motors that are hard on valve train. Also, a little lube in the blower itself couldn't hurt longevity.

In a previous life I was an A&P Mechanic. The Old Timers in aviation swear by it. DC-3 and other radial engined pilots kept a few gallons on board and whenever they heard mis-firing, dumped a gallon into thier radial engines. Presto, fixed. It mainly worked on keeping valve train components free and sludge build up down. Here's a url from that side of the house:

And an extract:
Hi Guys
This is an interesting debate and I am keen on any method which will prolong the life of my W670. The oil is expensive here in Australia, but a helluva lot cheaper than an engine repair!!I hear conflicting views. I run my engine on 100LL and the question of adding MM oil was asked of Radialengines..See their website at Here is an extract.

Q. Does using Marvel Mystery Oil in the Fuel accomplish anything?
A. In our experience, yes, it does. At the temperatures found in the combustion chamber of a cylinder, MM oil will be vaporized. The best theory is that the MM oil acts as a vapor blast and keeps carbon and lead deposits soft and passing through the exhaust valve rather than adhering to the valve, seat, or guide. In these days of 100 LL fuel (with several times the lead content of the original 80/87 octane fuel) this is an important function. Overall, engines operated with MM oil experience significantly less valve and seat problems and have cleaner burning spark plugs.

Hope this helps,
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Old 07-21-2002, 01:53 PM
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Hey I still am an A&P mechanic. Marvel Mystery oil was started by the manufacturer (sp) of Marvel Shebler carburetors, still used today in almost every carbed aircraft. when He built them they would come shipped new with a perservitive oil inside them. No one knew what the stuff was hence the name. basically it is an airomatic hydrocarbon that will 1) burn 2) be great as a penetrating oil, this is why it frees up stuck engines. and 3) get rid of deposites caused by burnt oil or lead depositis. some of you guys know that when you put wd-40 or pblaster or liqiud wrench on a stuck bolt, it will also loosen up the grease around it. it also smells "funny" well, this stuff does just that inside the engine. It also works good for fogging because it leaves an oily film on everything. I personaly think that the stuff is made from this, and any aircraft mechanic might agree. 5606 mineral hydraulic fluid,( hence the red color), mouse milk, an old penetrating oil( smell the stuff) a hint of 100 wt mineral oil and a little 100 low lead. I have mixed this stuff together and have come up with the same viscosity, color, and smell. I overhaul aircraft carbs at my shop and this is the stuff I ship 'em with. hell, pour it in any engine, wont hurt it, and it may even increase the octane rating a bit. It burns slower then regular gas, so theoreticaly it does just that.
have fun be safe!!!!!!!!!!!!
P.S. I run it in my blown hemi.
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