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Synthetic oil + Marvel Mystery Oil = happy lawn mower

I’ve always hated my lawn mower. But once I started using Marvel Mystery Oil in a lawn mower, and putting synthetic 10w-30 oil in the crankcase, I’ve been much happier. It makes me feel like I discovered one of the secrets of the universe.

While you’re at it, check the air filter. You’re supposed to change that every year, at least. The combination of a fresh air filter, Marvel Mystery Oil, and synthetic oil gives me easier starts and smoother running.

Marvel Mystery Oil does wonders for my lawn mower. Image credit: Hugo90/Flickr

One of my coworkers–we’ll call him Doug, since that’s his name–said if the mower is hard to start, to put synthetic oil in it to make it easier. I believed him. I’ve been using synthetic oil in my cars for almost 20 years, and I never have trouble starting them in the winter.

So I picked up a quart of synthetic 10w30 motor oil and a bottle of Marvel Mystery Oil. The competing Sea Foam Motor Treament would have also worked, but Marvel’s product is a bit cheaper.

I poured about 3 ounces of Mystery Oil into the Toro, topped it off with 17 ounces of the synthetic 10w30, checked the oil level, and all was good. Then I put a couple of ounces in the gas tank. That’s severe overkill–the manufacturer recommends 4 ounces per 10 gallons–but it’s too late now. Next time I’ll use less. Then I put about 4 ounces in my Honda Civic’s gas tank. Might as well.

I doubt too much will hurt it. I’m pretty sure I saw Dad pour a whole quart into his gas tank on several occasions. As dirty as the engine and carburetor probably are, the overkill might help the first time.

If you’re wondering what Marvel Mystery Oil is, its exact makeup is a trade secret. But as far as anyone can tell, it’s a mixture of a light oil and solvents, and it breaks up carbon deposits and anything else that shouldn’t be in engines and fuel systems.

I replaced the air filter, then primed the engine. Pull! The motor turned over and made about the most pathetic sound of protest I’ve ever heard come out of a machine, but it didn’t die. And after a couple of seconds it sounded good. Really good. So I walked the length of the yard with it. Smooth.

I mowed around half the back yard. Half of it is semi-wild and doesn’t need to be mowed quite as often. I got the job done in 40 minutes, which is less time than it usually takes. And I didn’t feel nearly as drained as I usually do after 40 minutes, so clearly the mower didn’t make me work as hard as it has been. And the mower didn’t stall or sputter at all. Even when cutting tall grass that normally causes stalls, it didn’t stall.

I noticed when I was getting the air filter that Sears is promoting something it calls Easy Start or something like that, claiming their mowers are 20% easier to start. I don’t know how you measure that. But it seems to me you’ll do just as well putting synthetic oil in whatever you’ve got and mixing a couple of ounces of Marvel into the oil and about a cap full into the gas tank to clean out the engine and carburetor and keep them clean. The Marvel also acts as a fuel stabilizer, so you don’t have to use Sta-bil or something similar. And that’s nice, because Marvel is cheaper.

So if you hate your lawn mower, what worked for me might work for you too. And if you live up north, try it in your snowblower.

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1 thought on “Synthetic oil + Marvel Mystery Oil = happy lawn mower”

  1. Dave, you inspired me to keep on fighting with my mower. The Sears push mower that we bought used had quit working. My store was Autozone instead of Advance, but all the other details were the same. The big bottle of Marvel Mystery Oil, a quart of house-brand synthetic 10-W-30, and some attention to the mower. No oil drained out, though – I had apparently emptied the oil through tipping the mower over to scrape the deck. No wonder it wasn’t running. But the addition of MMO and synthetic, plus a dab of MMO in the gas tank, and it’s zooming again. It does seem smoother, but almost anything would after no oil at all.

    Thanks for the post. I’m going to try the same thing on the non-starting Honda mulching mower next.

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