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A. Spruce
Marvel's Mystery Oil

Marvel's Mystery Oil, anybody use it?

I have an aging lawnmower that I'm considering using it in, at least to clean it out. The mower is 15+ years old with questionable maintenance before I started taking care of it about 8 years ago (yearly oil and air filter change, blade sharpening ).

I also have a friend's lawnmower that receives little to no maintenance that I will be changing the sludgy oil in soon.

Anyone use MMO either as a one time clean-out or as an oil additive in small engines? Benefits? Damage?

Re: Marvel's Mystery Oil

MMO is a top oil usually used as a gasoline additive. A little bit helps lubricate the valves, but you don't want to be using it in a modern fuel injected automobile. It is very similar to a product called Risoline which is another top oil. Both can be added to the oil pan, up to 20% to help loosen sludge deposits just before an oil change.

But there are other products that can be used. ATF @ 20% is very good at desludging an engine, so is the old standby, kerosene. Kerosene can even be used at 100% for a few minutes. This used to be common way back in the old days of non detergent oil and no oil filters. An oil change back then was to drain the oil, fill the crankcase with kerosene, run the engine for a few minutes, drain the kerosene and fill with fresh oil. This should not be necessary if you have been using detergent (HD) oil.

Here is a little trick I have used with success. I save the oil from the oil changes in the cars and trucks that I maintain that use synthetic oil. Once in a while, after I drain the lawn mower, or any small engine, I refill it with the used synthetic oil. I run the engine for a few minutes and then drain it out and refill with 30HD. You do not want to run this under load, like mowing the lawn with car oil in it as most small engines do not tolerate multi-viscosity oil when they get hot.

Anyway, the used synthetic oil really cleans out the engine. The fresh 30HD afterwards will stay clearer for a long time instead of turning dark moments after starting the engine after the oil change. BTW, on a particularly dirty lawnmower engine that I though was near the end of the road, I did the thing with the used synthetic oil two times before refilling with 30HD. It runs like a new engine now. Best part is the cost of the used synthetic oil, free.

Re: Marvel's Mystery Oil

Great tip about using used synthetic oil to clean out a small engine! Thanks.

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