Gumout multi-system tune-up Vs Marvell Mystery Oil (MMO)?

I started using the MMO on my Acura integra since there was carbon deposit when looked through the spark plug hole. After about a 32oz (80gals of gas), gas mileage improvement was noticed only during the last two application (overall about 6%). I was recommended to continue to use the MMO.

Lately I saw Gumout multi-system tune-up which does clean up the carbon build up + other things.

Unfortunately, Amazon does not sell Gumout multi-system tune-up hence no reviews.

I am wondering where do I go from here… continue with MMO or once in a while application of Gumout? My Acura has new Fuel Injectors.

Should I start using MMO on my 2013 Mazda with 100k or use Gumout periodically?

BTW, I never used MMO inside the engine.

I prefer Techron.


Techron is good. I’ve had success removing carbon (and grease and paint when soaking parts) with Berryman products. Seems to be pretty potent, fast acting stuff. I’ve used their carb cleaner, no experience with this total fuel system cleaner.

Home Depot has reviews . And how hard is it to drive to Home Depot or a local place that sells that product. Why make things difficult ? The Gumout stuff will not harm anything so why not try it and see if it helps ?

You can’t buy a “mechanic in a can”.

:laughing: sorry , I in one of those


Adding various treatments to the tank can help some, try whatever you like.

Next would be the Seafoam induction treatment described several places on this site.

Finally, you could take to a shop for either a thorough chemical treatment, or removing the head and scraping out the carbon.

You mean this:

On a Honda, the Red bottle eliminated the CEL for me without any repair.

Still wonder future of MMO? The gentleman who recommended said continued usage. It took 80gals to make a difference - gentle hence better?

From the Berryman advert:

“High Energy Solvent Technology,” a Berryman exclusive, incorporates the use of strong solvents, as opposed to weak carriers and dilutes such as mineral spirits or kerosene”

I assume the MMO has the dilutes in it that they’re referring to. As does Seafoam. As does the Berryman stuff to some extent, I’d imagine. Some are weaker than others, but who knows which. You might experiment with some different brands over a few tanks and do a non scientific test.

I’ve used Sea Foam for over fifty years to remove carbon.

And here’s why.


This is awesome.
Also seems quicker than MMO which took 80gallons!

To be fair, I don’t think you sprayed the MMO directly into the intake. Seafoam isn’t going to clean the carbon that fast putting it in your fuel tank.

I let Seafoam be sucked into the intake, let it sit 30 min and then do the Italian Tune Up like it says in the instructions on the can.

Don’t forget the dead chicken.

How often you do it?
Should there be a concern of things getting damaged with the use of Seafoam? Amazon has such reviews though.

AFAIK it does. It does not happen in the modern cars with direct or whatever injection.

Sorry I misread the op. No it won’t get into the intake manifold. But it will get into the piston/cylinder.

Then why did the guy in the video perform the induction cleaning procedure and not just pour the chemical into the fuel tank?

Good catch. I updated my reply.
Sorry I misread the op. No it won’t get into the intake manifold. But it will get into the piston/cylinder. I don’t deals with these things on a daily basis so my vocab got rusty.

For engines with injectors upstream of the valves, every 30k miles or so. I have one car with direct inject known to carbon up the valves bought used at 30K. I did that car when I bought it. I think I’ll do it again 12K later.

Right, what I meant - in the video they are injecting the seafoam directly into the intake. It’s not getting diluted with 15 gallons of fuel like it does when you pour it in the tank (like you did the MMO). Straight into the intake is a quicker, more aggressive way of doing it than mixing it with the gas in the tank.