Marvel Mystery Oil: Yay or nay?

[JasonTL]

What are y'alls thoughts on it?
Some things I've read say it is really good at cleaning old engines and can improve efficiency and life.

Is it worth trying at $5 a bottle? Or is the general consensus it's worthless?

Also, it can be added to your gas or oil or both, right? Any particulars about whether adding to one is better than the other or if both at the same time?
I've already decided to use MOS2 in my oil after I do my next oil change. Would these two together be bad, good, or not much of an effect?

Would love some experience posts. I've read reviews of it being beneficial but those can't always be trusted.

 

[Realtech214]

I just tried using it in my truck. It made the oil pretty dark over the 600 miles it was in there, must have clean some. I think Seafoam is a much faster and eaiser way to clean the crankcase. I also put mmo in my fuel, didnt notice anything. Seafoam gets my vote

 

[Clevy]

Do not use it with mos2. It basically defeats the purpose. The mos2 is trying to plate the internal parts and the mmo is trying to clean it off.
Mmo is great stuff when used as directed. I have a top end oiler that mists mmo into my intake while the engine runs,through a vacuum line. I really like it.
I've used it in my fuel. Some say that it lessened engine vibration at idle. I now use it in a mix with tc-w3/mmo/acetone. Helps my fuel consumption and works as an upper cylinder lube.
In the crankcase it works great to dissolve deposits. Use as directed and you shouldn't have any problems whatsoever.
Dermapaint's been using it for 40 years. If you have any questions I suggest sending him a message. He is about as expert as they come when it comes to using that stuff.
In my experience it works just as advertised. It won't work miracles but I can say that I don't have any fuel delivery issues either......coincidence?

 

[ahoier]

another MMO thread? lol...really.....you're gonna get responses all over the place. The majority of the people hate it....but there is a small consensus that swear by it, me included. I don't use it "religiously" - but every now and again, typically every other tank....my typical crankcase use, is simply as a top off oil half way through my 6k OCI.....on my 88 Dodge Aries

Right about 3-4k, I'll be a quart low, and will add it to the crankcase.

 

[Clevy]

Originally Posted By: Realtech214
I just tried using it in my truck. It made the oil pretty dark over the 600 miles it was in there, must have clean some. I think Seafoam is a much faster and eaiser way to clean the crankcase. I also put mmo in my fuel, didnt notice anything. Seafoam gets my vote


Right. There is already alcohol in fuel,lets add more. I will however vouch for seafoam in the crankcase and through a vacuum line however in the crankcase it evaporates fairly fast,within 1000 miles,so if trying to clean deposits seafoam shoud be added a couple times per oci to get a real cleaning effect.
Seafoam is useless in fuel unless you pour in a gallon or so. Mmo is more of an upper cylinder lube than a fuel system cleaner,although I'm sure with consistent use mmo cleans the fuel system.
Additives like techron or regain,and now royal purple has one that contains Amines. They work very well to clean fuel system and combustion chamber deposits. From what I've seen the amines seem to moisten the carbon deposits allowing them to come loose and head out he exhaust. But that was just what I noticed on a carboned up piston from my harley I used as a test piece. The regain made it look wet and it started peeling away after a while sitting on my bench. Seafoam didn't do anything but I didn't try mmo,so it may or may not do same.
Anyways mmo is great stuff. Use as directed.

 

[expat]

I have told my story on this site before, But here goes again:

About 6 years ago I bought a Toyota pick up that had been in storage for 20+ years. The engine had a rough idle and poor power at low rpm. I suspected sticky rings.
I tried a course of Auto Rx (that was in Vogue here at the time) but there was no change. The engine would also use oil at a rate of about 1 Litre per 1,00 miles.
For two years I just lived with it, resigning myself to rebuilding the engine, when I could get around to it.

Then, on a whim, while in the U.S., I bought some MMO just because it's cheap and 'What the heck'
I added 1/2 liter to the oil 1,000 miles before the regular OCI.
I needed to add oil anyway, so the cost was almost zero.

200 miles into the treatment, driving through town and stopping at a traffic light, I 'Thought' my engine had stalled!
IT HAD NOT!! it was running smoothly for the first time since I had owned the truck.
Low speed torque was also vastly improved, to the point where I could run my long gravel driveway at idle in 2nd gear for the first time EVER.
Oil consumption became (and still is) non existent.

I was impressed.

I did also add MMO to my gas, but here were no noticeable effects.

Just my story, make of it what you will.

 

[Kuato]

IMO Nay.