My Experience with Marvel Mystery Oil

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Delta11

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I started using MMO in my 2010 Ram Longhorn 2500 5.7 when I bought it with 95k on it. It was and is the nicest truck that I have owned. Anyway... with plans to keep it Long Term got me interested in MMO. Started by adding it to my first three or four oil changes of which I did in approximately one month in order to clean the engine. The last oil change the oil was clean so I figured that I had done some good. Since then I have added one quart to the oil change every 5000 miles. I have 230k on it now. I tried synthetic once and It Seemed like the engine shook on startup and ran rough until it warmed up so I immediately drained it out and went back to full Dino oil as they say 5w20. Thought about going heavier with 5w30 since the MMO has a thinning effect but I felt that was what MMO was about so I stayed with 5w20. So I started adding it to the gas hoping for the benefits of upper cylinder lubrication and extending the life of my engine of course. Yes I thought that it would be equivalent to putting Diesel into a gas engine but at 4 ounces per 10 gallons it was going to be a wash or may help long term. I had the transmission changed at 195k, rear wheel bearings, And O2 sensors since they had it up in the air. Months later the engine codes started popping up 071,072,0420 and a couple of others I forgot exactly, one said pre cat 0397 maybe and a misfire code but did not state the cylinder. Put some cat cleaner in my tank and B12 to try and clean it up. Codes changed after that...some cleared some stayed and some new ones. I had them all written down but I trashed it. Anyway I looked up all of the possibilities on the internet that could bring them in. Changed the MAP sensor and it seemed to help at first, caused my mileage to increase up to 17.2 at 70 mpg which has never happened but that was short lived and I don't know why yet. To end this story I changed the plugs which were fouled and the O2 sensors before the Cat...one had stopped putting out voltage according to my scanner. Cleaned the two after the cat with Electrical cleaner since they all were new and reading voltage. All of the injectors and coil packs tested good. So I believe that the MMO in the gas fouled the plugs in return fouled the O2 sensors and threw up the cat code because of the unburned gas/mmo which fouled the Cat somewhat. What I did cleared the codes and all is well. I have new coil packs on the way since I am keeping this truck as long as possible...It has a dip stick on the Transmission Right! My opinion...Don't put Marvel Mystery Oil in your gas tank even at the recommended 4 Ounces per 10 gallons.
 

Mister Luck

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I’m sorry you are having problems with you truck.

I would advise a coolant pressure test.
Coolant is seriously detrimental to o2 sensors.

2oz is the most MM I’ve ever used in my gas tank mixed with an octane booster or injector cleaner, but you need to be careful of the ingredients because some will kill the seals on injectors, even large methanol percentages are not advisable with most modern injector seals.
and I’ve never put MM in the crankcase.

If not using top tier gasoline 89 or better octane,
using additives in recourse is not going to stop timing advance.

It amazes me that some will only use the best crankcase oil but when it comes to the pump it’s the cheapest price they can find.
 

Nicholas Cove

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If you're running oil thru your fuel your cats are likely trashed. There is nothing that that crap is doing for upper cylinder lubrication. The only thing that works for that is lead and we ain't using it anymore. Everything has hardened valve seats now. If you want to do your engine a favor run premium in it and and stop messing with snake oil ****.
 

Moose2

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I use mm oil to Squirt in cylinders when storage an engine. Haven’t used it in anything with ox sensors for obvious reasons. In fact, haven’t used it in anything but carbureted engines. Haven’t seen a need to use it in any crankcase lately, probably due to better oils and better maintenance on the cars I buy. I have slowed buying cars though, so mm oil is used as a surface treatment on the log splitter, anything else that I don’t want to rust. I only use oiled filters on off road toys, so it gets used for that.
 

DJ18hemi1500

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I started using MMO in my 2010 Ram Longhorn 2500 5.7 when I bought it with 95k on it. It was and is the nicest truck that I have owned. Anyway... with plans to keep it Long Term got me interested in MMO. Started by adding it to my first three or four oil changes of which I did in approximately one month in order to clean the engine. The last oil change the oil was clean so I figured that I had done some good. Since then I have added one quart to the oil change every 5000 miles. I have 230k on it now. I tried synthetic once and It Seemed like the engine shook on startup and ran rough until it warmed up so I immediately drained it out and went back to full Dino oil as they say 5w20. Thought about going heavier with 5w30 since the MMO has a thinning effect but I felt that was what MMO was about so I stayed with 5w20. So I started adding it to the gas hoping for the benefits of upper cylinder lubrication and extending the life of my engine of course. Yes I thought that it would be equivalent to putting Diesel into a gas engine but at 4 ounces per 10 gallons it was going to be a wash or may help long term. I had the transmission changed at 195k, rear wheel bearings, And O2 sensors since they had it up in the air. Months later the engine codes started popping up 071,072,0420 and a couple of others I forgot exactly, one said pre cat 0397 maybe and a misfire code but did not state the cylinder. Put some cat cleaner in my tank and B12 to try and clean it up. Codes changed after that...some cleared some stayed and some new ones. I had them all written down but I trashed it. Anyway I looked up all of the possibilities on the internet that could bring them in. Changed the MAP sensor and it seemed to help at first, caused my mileage to increase up to 17.2 at 70 mpg which has never happened but that was short lived and I don't know why yet. To end this story I changed the plugs which were fouled and the O2 sensors before the Cat...one had stopped putting out voltage according to my scanner. Cleaned the two after the cat with Electrical cleaner since they all were new and reading voltage. All of the injectors and coil packs tested good. So I believe that the MMO in the gas fouled the plugs in return fouled the O2 sensors and threw up the cat code because of the unburned gas/mmo which fouled the Cat somewhat. What I did cleared the codes and all is well. I have new coil packs on the way since I am keeping this truck as long as possible...It has a dip stick on the Transmission Right! My opinion...Don't put Marvel Mystery Oil in your gas tank even at the recommended 4 Ounces per 10 gallons.
Thank you for the info. Just curious if you had changed the spark plugs soon after you bought the truck at 95k.
 

Zoe Saldana

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I started using MMO in my 2010 Ram Longhorn 2500 5.7 when I bought it with 95k on it. It was and is the nicest truck that I have owned. Anyway... with plans to keep it Long Term got me interested in MMO. Started by adding it to my first three or four oil changes of which I did in approximately one month in order to clean the engine. The last oil change the oil was clean so I figured that I had done some good. Since then I have added one quart to the oil change every 5000 miles. I have 230k on it now. I tried synthetic once and It Seemed like the engine shook on startup and ran rough until it warmed up so I immediately drained it out and went back to full Dino oil as they say 5w20. Thought about going heavier with 5w30 since the MMO has a thinning effect but I felt that was what MMO was about so I stayed with 5w20. So I started adding it to the gas hoping for the benefits of upper cylinder lubrication and extending the life of my engine of course. Yes I thought that it would be equivalent to putting Diesel into a gas engine but at 4 ounces per 10 gallons it was going to be a wash or may help long term. I had the transmission changed at 195k, rear wheel bearings, And O2 sensors since they had it up in the air. Months later the engine codes started popping up 071,072,0420 and a couple of others I forgot exactly, one said pre cat 0397 maybe and a misfire code but did not state the cylinder. Put some cat cleaner in my tank and B12 to try and clean it up. Codes changed after that...some cleared some stayed and some new ones. I had them all written down but I trashed it. Anyway I looked up all of the possibilities on the internet that could bring them in. Changed the MAP sensor and it seemed to help at first, caused my mileage to increase up to 17.2 at 70 mpg which has never happened but that was short lived and I don't know why yet. To end this story I changed the plugs which were fouled and the O2 sensors before the Cat...one had stopped putting out voltage according to my scanner. Cleaned the two after the cat with Electrical cleaner since they all were new and reading voltage. All of the injectors and coil packs tested good. So I believe that the MMO in the gas fouled the plugs in return fouled the O2 sensors and threw up the cat code because of the unburned gas/mmo which fouled the Cat somewhat. What I did cleared the codes and all is well. I have new coil packs on the way since I am keeping this truck as long as possible...It has a dip stick on the Transmission Right! My opinion...Don't put Marvel Mystery Oil in your gas tank even at the recommended 4 Ounces per 10 gallons.
Are you putting MMO in the oil when you change the oil? Or are you adding MMO JUST BEFORE (100 miles or so) you change the oil? My understanding is that you put it in JUST BEFORE to clean.

GAS - I put MMO in the gas all the time, it seems to quiet the engine and small mpg improvement. No problems at all. Should be about 4 oz/10 gallons.
 

huntergreen

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I thought 2500 5.7 engines specked 5-30 oil .
 

Burla

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I thought 2500 5.7 engines specked 5-30 oil .
lol, yeah no joke. You are already too thin, then you substitute a qrt of 5 wt oil with solvent, and you can't understand why you have issues? Add a qrt to your oil, your 20 weight is now 16 weight if you believe MMO because that is what they say, when you should be running 30 weight. When you clean or dislodge any contamination it often sticks in o2 sensors, and sometimes especially with solvents like MMO those can cure themselves as solvent can then clean away the o2 sensor over time.

I have lived through this in the past with engine cleaners and o2 sensors. I paid for a customers o2 sensors to be replaced when the engine cleaner white paper said you can get o2 sensor fail and that is usually temporary. So that was an expensive lesson, but if you use engine cleaners this is a risk for sure. And yeah it can foul plugs as well, shouldnt you know that it advance, that is literally what you ask it to do, you want clean or not? Where do you think that stuff will go? In the combustion chamber you may want a stronger cleaner like PEA, then it cleans the chamber plus cleans anything off the plugs. Or, sea foam though vac lines which is 100% cleaning solvent into chamber, can foul plugs but most of the time it is temporary. The issue with MMO is it is a light cleaner, so it will have a hard time cleaning contamination off items such as o2 sensors or plugs.

I'm not sure what the issue was with synthetic, in fact it is likely the engine needed cleaning in the first place because of the use of dino oil. Use synthetic from day one you likely wont have the sludge or varnish issues in the first place, the two main features of synthetic is clean base oil without contamination and higher tbn which by itself is a detergent. I'd move to 5w30 synthetic and go to a shorter interval, this will be a safer way to clean the vehicle, and most importantly, clean the pcv valve or replace which allows oil to clean engines.
 

Burla

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With ethanol I do like the idea of running upper cylinder lubes, I think this is one of those d@mned if you do d@mned if you don't type of things.
 

HEMIMANN

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Only time I ever used MMO was as a solvent cleaner diluent to loosen sticking piston rings on GM's terrible 5.3L V8 AFM engine. The engine went from using no oil to a quart every 1,000 miles @ 70,000 miles. Found out they cheapened the ring pack at the same time they added AFM, so the cold AFM cylinders fouled and stuck rings.

Yup, MMO loosened the rings and it stopped using oil, so I sold it and went Ram, never looked back. That's all MMO is good for - a temporary cleaner.
 

Treburkulosis

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Well tomorrow starts my annual seafoam in the crank case ritual. My truck is like clock work. It’s about 700 miles from its 5k oil change and it let me know this morning. I’ll add seafoam as I have done for the last 82k miles take it easy the next two days going into work and run my 100 miles cleaning. It will get its oil change Friday.
 

Zoe Saldana

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lol, yeah no joke. You are already too thin, then you substitute a qrt of 5 wt oil with solvent, and you can't understand why you have issues? Add a qrt to your oil, your 20 weight is now 16 weight if you believe MMO because that is what they say, when you should be running 30 weight. When you clean or dislodge any contamination it often sticks in o2 sensors, and sometimes especially with solvents like MMO those can cure themselves as solvent can then clean away the o2 sensor over time.

I have lived through this in the past with engine cleaners and o2 sensors. I paid for a customers o2 sensors to be replaced when the engine cleaner white paper said you can get o2 sensor fail and that is usually temporary. So that was an expensive lesson, but if you use engine cleaners this is a risk for sure. And yeah it can foul plugs as well, shouldnt you know that it advance, that is literally what you ask it to do, you want clean or not? Where do you think that stuff will go? In the combustion chamber you may want a stronger cleaner like PEA, then it cleans the chamber plus cleans anything off the plugs. Or, sea foam though vac lines which is 100% cleaning solvent into chamber, can foul plugs but most of the time it is temporary. The issue with MMO is it is a light cleaner, so it will have a hard time cleaning contamination off items such as o2 sensors or plugs.

I'm not sure what the issue was with synthetic, in fact it is likely the engine needed cleaning in the first place because of the use of dino oil. Use synthetic from day one you likely wont have the sludge or varnish issues in the first place, the two main features of synthetic is clean base oil without contamination and higher tbn which by itself is a detergent. I'd move to 5w30 synthetic and go to a shorter interval, this will be a safer way to clean the vehicle, and most importantly, clean the pcv valve or replace which allows oil to clean engines.
Great post.
 

Fireman48

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If you're running oil thru your fuel your cats are likely trashed. There is nothing that that crap is doing for upper cylinder lubrication. The only thing that works for that is lead and we ain't using it anymore. Everything has hardened valve seats now. If you want to do your engine a favor run premium in it and and stop messing with snake oil ****.
Now this guy knows science.
 

nwhunter55

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I used mmm back in the 70's in a 351 cleveland that had a stuck valve or valves from severely overheating. A little in the cylinders, let it sit, rolled it over and it solved that problem.
 

Fergusontd

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I won't use any additives in any of my engines. None of that snake oil **** is good for any engine
 

Elkman

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So much ignorance it is amazing. The only additive worth considering is fuel injector cleaner and this would be at 20k mile intervals. Once lead was no longer being putting gasoline the engine life more than doubled and this was no surprise to the engineers that developed tetraethyllead at General Motors in the 1920's.

Octane is not a measure of the power content of gasoline but rather its resistance to pre-ignition. The higher the octane the lower the pre-ignition and the higher the compression ratio for an engine without "knock" which damages the pistons and crankshaft.

Every vehicle sold in the last 30 years has a computer that adjusts the spark advance to prevent pre-ignition and so burning a lower than recommended octane rated gas results in the computer retarding the spark timing which in turn results in less power output per gallon burned. But if an engine is designed to run on 87 octane rated gas then putting in 93 octane does nothing for engine performance but it does increase profits for those poor struggling oil companies like Exxon and Chevron.

There is an organization, the SAE, that tests motor oil and if an oil meets its requirements it is going to be equally good to another motor oil that also meets those lubricating specifications. You can spend twice as much for a "premium" motor oil but there is zero gain in lubrication and in engine life if you do.

Only with diesel motor oils is the additive mix important and this is where price is no indicator of how good a mix one gets but relates only to the marketing budget of the company as with Amsoil with a poor diesel additive mix.
 

Sherman Bird

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I started using MMO in my 2010 Ram Longhorn 2500 5.7 when I bought it with 95k on it. It was and is the nicest truck that I have owned. Anyway... with plans to keep it Long Term got me interested in MMO. Started by adding it to my first three or four oil changes of which I did in approximately one month in order to clean the engine. The last oil change the oil was clean so I figured that I had done some good. Since then I have added one quart to the oil change every 5000 miles. I have 230k on it now. I tried synthetic once and It Seemed like the engine shook on startup and ran rough until it warmed up so I immediately drained it out and went back to full Dino oil as they say 5w20. Thought about going heavier with 5w30 since the MMO has a thinning effect but I felt that was what MMO was about so I stayed with 5w20. So I started adding it to the gas hoping for the benefits of upper cylinder lubrication and extending the life of my engine of course. Yes I thought that it would be equivalent to putting Diesel into a gas engine but at 4 ounces per 10 gallons it was going to be a wash or may help long term. I had the transmission changed at 195k, rear wheel bearings, And O2 sensors since they had it up in the air. Months later the engine codes started popping up 071,072,0420 and a couple of others I forgot exactly, one said pre cat 0397 maybe and a misfire code but did not state the cylinder. Put some cat cleaner in my tank and B12 to try and clean it up. Codes changed after that...some cleared some stayed and some new ones. I had them all written down but I trashed it. Anyway I looked up all of the possibilities on the internet that could bring them in. Changed the MAP sensor and it seemed to help at first, caused my mileage to increase up to 17.2 at 70 mpg which has never happened but that was short lived and I don't know why yet. To end this story I changed the plugs which were fouled and the O2 sensors before the Cat...one had stopped putting out voltage according to my scanner. Cleaned the two after the cat with Electrical cleaner since they all were new and reading voltage. All of the injectors and coil packs tested good. So I believe that the MMO in the gas fouled the plugs in return fouled the O2 sensors and threw up the cat code because of the unburned gas/mmo which fouled the Cat somewhat. What I did cleared the codes and all is well. I have new coil packs on the way since I am keeping this truck as long as possible...It has a dip stick on the Transmission Right! My opinion...Don't put Marvel Mystery Oil in your gas tank even at the recommended 4 Ounces per 10 gallons.
Try running PEA (Polyether amine) in the fuel tank BG 44K has been proven time and again to clean catalytic converters, plugs, o2 sensors, etc. I run it occasionally in both of my ancient, high mileage daily drivers; with many, many miles on them. I just got in from a 3 day East Texas road trip in my 2004 ford Ranger with 160,000 miles on it. 3.0L engine, 5R55e automatic trans with a 3.55 diff ratio, P235/75R15 Goodyear Wrangler tires.... got 20 mpg overall, no glitches other than soreness from the EDGE suspension! Both vehicles have original cats on them. The other vehicle my wife drives is a 2007 KIA Sorento with 222,000 miles.
 

Zoe Saldana

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Try som MMO in the gas - 4oz/10 gal and tell me the engine doesn't sound quieter!
 
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