[jfjohn]

Does anyone here use Marvel Mystery fluid in their oil and gas? It does seem to increase gas mileage when adding to the gas. I'm guessing one reason is because of the upper cylinder lubrication (less friction). Do you think it raises the octane of the gas? What about putting it in the crankcase? What are your thoughts on it?

[Kruser]

Originally Posted by jfjohn

Does anyone here use Marvel Mystery fluid in their oil and gas?

Wow. Like religion and politics, subjects like this always open up a can of worms.
Here's my OPINION on the subject. First, oil companies spend millions of dollars in research and development to improve their oil. I believe there are many oils on the market that will get you to 300K miles without the help of any additives. With that being said, I have one car that I do use MMO in. This car (with a 302) had less than 100K miles when I purchased it, but when I pulled the intake manifold, there was over 2 inches of sludge on the lifter valley. I took a puddy knife and got it as clean as I could, buttoned everything up and have used MMO in it ever since. The crankcase is getting cleaner. Would oil alone have done it? Maybe. Maybe MMO is cleaning it faster, I don't know.
My opinion is that a oil additives are not needed for most engines that have been maintained. If needed, I will use Marvel Mystery oil or another product called Kreen, which is a little tougher to find. I've never used MMO in my gas tank, so I can't comment there.
My $.02 worth.

[MichaelJennnings]

Originally Posted by jfjohn

Does anyone here use Marvel Mystery fluid in their oil and gas? It does seem to increase gas mileage when adding to the gas. I'm guessing one reason is because of the upper cylinder lubrication (less friction). Do you think it raises the octane of the gas? What about putting it in the crankcase? What are your thoughts on it?

One thing you did not state in this is what kind of vehicle you want to do this with. Personally, I don't use additives in either the gas or oil. I have an 88 F-250 w/150K and an 01 Taurus w/98K. Neither one has had additives used on them. Both are EFI.
Here is the problem with putting MMO in the gas. This is NOT a 2-cycle engine. You will eventually oil foul the plugs, O2 sensors, injectors and catalatic converter. Unless you want major repairs, I would highly recommend stopping this practice. As for oil, today's oils contain high amounts of detergents and should for all intent purposes be sufficient to take care of normal dirt PROVIDING they are changed regularly. Obviously the Kruser got a car that was not maintained. When this happens, MMO does work wonders to break this sludge down and let the filter take it out but again, keeping it changed out is paramount.

[jfjohn]

I don't the plugs or cats will be effected negatively. It's not that much oil. Only 4 ounces per 10 gallons. That's only 1 part MM and 320 parts gas.