Is adding a few ounces of
the gas tank on fill up for a Harley, or any gasoline engine of any benefit?
Marvel Mystery Oil added on gas fill up on Harley
- Thread starter RCT
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I tried some Marvel Mystery Oil in our Miata for a couple of tanks at about 4 oz.per 10 gals. The engine seemed rougher at high RPM like the octane was lower so I stopped using MMO. This engine was carboned up and I wanted to see if the MMO would free up any sticking valves. Some old timer Harley people like the stuff as an upper cylinder lube and it may be good for storage - stopping tank rust
RCT, I'm a believer in upper-cylinder lube but I confine it to (mostly) simpler, carbureted engines. Fuel injectors are finicky things and can clog ... sometimes a very expensive fix.
I used MMO in an '80s Ford Escort and I would routinely pick up about 3% better fuel economy. Also, the very slow oil consumption this car had would drop to absolutely zero as long as I had 2-3 ounces of MMO in each tank.
But because of the possibility of fouling injectors, I don't recommend this too much anymore. Might not be bad to try this in your Harley then keep strict records of your fuel economy and oil consumption. Possible protection of cylinder walls and/or valve seats will be harder to prove.
--- Bror Jace
I used MMO in an '80s Ford Escort and I would routinely pick up about 3% better fuel economy. Also, the very slow oil consumption this car had would drop to absolutely zero as long as I had 2-3 ounces of MMO in each tank.
But because of the possibility of fouling injectors, I don't recommend this too much anymore. Might not be bad to try this in your Harley then keep strict records of your fuel economy and oil consumption. Possible protection of cylinder walls and/or valve seats will be harder to prove.
--- Bror Jace
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