Originally Posted by hellosailor
MMO has its fans but I suspect also a large placebo effect. Added to the gasoline it acts as a "top cylinder lubricant" lubricating the cylinders and the valves in a way that the regular oil doesn't.
But mixed into the oil...there one has to ask, maybe the oil wasn't the right stuff to being with. MMO can't bring or do anything that a quality motor oil couldn't be doing alone.
For the price of a quart it isn't a painful experiment in any case.
I consider marvel as part solvent, part lubricant. I never put it in my oil except once when I had a stuck valve. I think I put in 50/50 marvel and motor oil, then ran the engine at idle, shut it down, ran it at idle, over and over till the valve freed up... can't remember exactly... I do know that I changed the oil and replaced with 100% motor oil before running under load.
The rear valves/rings don't heat up enough and can get gummed (again, memory may be wrong).
I put it in my fuel for a decade with no ill effects, can't prove it helped, but as I was never attacked by a zombie....