® Marvel Mystery Oil

While we're a lot more subtle than we were in the 1930s and 1940s, we're demonstrably just as gullible.

Quite often suspect carburetors on my bench are victims of the use of Marvel Mystery Oil. How can I tell? The vacuum chambers accumulate a tenacious, inky black slime inside. Only three things cause this and it's easy to narrow it down. More than 90 percent of the time it's Marvel Mystery Oil that is the culprit.

Adding mostly innocuous agents to engine oil has been a popular if officially unsanctioned pastime for generations while proving to do little harm. Or good. But such is not the case with things added to gasoline, as is the case with the Marvel. It really isn't a good idea to monkey with your fuel, on many levels. And if ever there was a "snake oil", that is, something made of incredibly basic and virtually inert ingredients, and about which no substantiated benefit is known (and often plenty harm, both observed and documented), Marvel Mystery Oil is it. Like bolt-on fuel mileage improvers, engine rebuilder in a can, and those odd, quaintly historic 1930s-era electromagnetic medical wonder cures, Marvel Mystery Oil is the stuff of whimsy. Know what it is? Baby oil. Yup. Some 70 percent mineral oil. So what? Well, that alone should give pause.

But maybe you have to be a mechanic to understand. Any first semester mechanics school student knows that adding almost anything to fuel is unwise and even in the best cases, such as in the legitimate use of fuel stabilizers, must be done carefully. But in the case of adding oilto fuel there really is no debate among professionals. Its a no-brainer. Don't. Oil in the combustion chamber slows the flame, and is a sure recipe for detonation. That's why blown head gaskets on some engines frequently result in engine damage: the oil entering the combustion chamber results in destructive knock. Additionally, oil in the combustion chamber also results in excessive carbon buildup on the valves, something you really want to avoid in Honda engines due to their already having valve durability problems. Deliberately putting oil into your cylinder is a really bad idea.

Marvel indeed.

Last updated November 2021
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