Tuesday, February 19, 2013

What is the Deal with the Marvel Mystery Oil?

Marvel Mystery Oil (MMO) Reviewed by Dmiko on .

I have read on various forums about people using Marvel Mystery Oil in either their motor oil or in their gasoline to achieve various positive results. I would never put it in my oil (because it makes the motor oil thinner, reduces its TBN retention and I generally don't need to clean anything in the crankcase).

But I was willing to try it in the gas. The stipulated benefits of using it in the gas are manifold. Is supposedly cleans your fuel system and prevents it from becoming dirty again. It also allegedly lubricates the cylinder walls while the engine is running, reducing friction and thereby improving fuel economy. It is supposed to also lubricate your fuel pump, making it last longer. And it smells nice.

So I tried it by adding about 4 oz per fill up in my 2004 Infiniti G35. I ran it for a few months while measuring fuel economy as well as getting the smog check test later.


I noticed a slight fuel economy improvement, but it was less than what I achieved later by simply driving at more reasonable speeds. The engine seemed run smoother, which could be an objective result or a subjective one, I dunno. But there were a couple more discoveries, one positive and one negative.


I was using a synthetic oil at the time: Quaker State Q-Horsepower and in all-highway driving was expecting to go over 7K miles on it. However, at close to 6K miles, the timing chain in my engine started to rattle on start-up. The rattle went away only when the oil was changed. I blame MMO since it probably washed down from the cylinder walls into the oil. So if I were to continue using MMO, I would probably have to change the oil more frequently.


I got a smog certification test done after using MMO and later I had a smog test done from a more efficient Honda 2.4-liter 4-cylinder engine in my mom's 2006 Honda Accord. After using MMO, the VQ35DE engine from my Infiniti G35 had significantly better numbers at over 50K miles than I got from the Honda only after 30K miles. Perhaps it does clean quite well? I even ran the G on regular gas and not on premium that was "recommended for optimal performance" by Infiniti.


The MMO is inexpensive, does seem to clean and lubricate well and is something I will probably be using from time to time. If you use it, remember to change the oil more frequently and/or get a used oil analysis (UOA) done. I will definitely use it before the next smog check in the Accord to see if it can improve the numbers.

Update: I tried it in the Accord and it actually improved the mpg by 2 mpg to an all-time-high for that car 38.5 mpg.

Rating: 4 stars out of 5.

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  1. It is great to have the opportunity to read a good quality article with useful information on topics that plenty are interested on.


  2. Agree with you Leslie.
    Thank you for your feedback