Can MMO be used in a similar fashion as Seafoam to clean the top end of an engine?  1/3 can of Seafoam is usually poured down the PCV hose of a hot engine.  Then left alone for 5 minutes to “hot soak”.

Has anybody tried this?  Did you notice a difference?

Sorry if this has been asked before but search did not turn up anything.

Yes, you can use Marvel Mystery Oil in your application instead of Seafoam.

How much MMO should be used to do this?

(I’m working on a 1997 Honda Civic DX)

I’m guessing that the Seafoam comes in a 12 ounce can, so 1/3 would be 4 ounces.  You can use this amount of Marvel Mystery Oil.

Ok, sounds good.

I know it’s a bit late for this, but this is a bad plan. If you look at MMO, it really is more like an oil. When you add it to the upper cylinders, the engine is still cycling and on the compression stroke you will get an autoignition. This will cause the engine to “diesel” (engine run-on). Your gasoline engine will actually sound like a diesel engine when you cut it off. Not good. Connecting rod damage and valve damage immediately come to mind.

-Techniker

I guess I have to disagree with Techniker.  The Seafoam product contains isopropyl alcohol as well as less oil and more solvent that Marvel Mystery Oil.  Therefore, the autoignition temperature of the Seafoam product is much lower than that of Marvel Mystery Oil.  If the Seafoam product does not autoignite, neither will the Marvel Mystery Oil.

Rich Kelly - 21 June 2010 03:07 PM

I guess I have to disagree with Techniker.  The Seafoam product contains isopropyl alcohol as well as less oil and more solvent that Marvel Mystery Oil.  Therefore, the autoignition temperature of the Seafoam product is much lower than that of Marvel Mystery Oil.  If the Seafoam product does not autoignite, neither will the Marvel Mystery Oil.

You would think so, but I’ve run Seafoam and MMO through engines. Never had a dieseling problem with the Seafoam. The MMO, however did cause dieseling, and for quite a while (at least it seems like a while when you hear your engine dieseling).

-Techniker

Techniker - 21 June 2010 06:03 PM

Rich Kelly - 21 June 2010 03:07 PM

I guess I have to disagree with Techniker.  The Seafoam product contains isopropyl alcohol as well as less oil and more solvent that Marvel Mystery Oil.  Therefore, the autoignition temperature of the Seafoam product is much lower than that of Marvel Mystery Oil.  If the Seafoam product does not auto ignite, neither will the Marvel Mystery Oil.

You would think so, but I’ve run Seafoam and MMO through engines. Never had a dieseling problem with the Seafoam. The MMO, however did cause dieseling, and for quite a while (at least it seems like a while when you hear your engine dieseling).

-Techniker

Could be due to the difference in engine then, I’m a high compression engine. I think I also ran a lot more MMO into my engine- I ran it wide open into my brake booster vacuum line (probably closer to 12 oz) and it dieseled after I shut off the ignition. No problems though on start up and it runs great. Even if you do experience some dieseling, for such a short term, I highly doubt any real problems would result, it’s just something to be aware of.

-Techniker