Adding Marvel Mystery Oil to diesel and/or oil

[TideTime]

I am not a big fan of fuel or oil additives, but upon experiencing problem with my 35-year old Yanmar 1GM10, I consulted Mack-Boring for their recommendation of a shop to work on my engine. The certified diesel mechanic recommended by Mack-Boring determined my engine required a cylinder head and exhaust elbow. The work completed, the diesel mechanic recommended that due to the age of my engine that I use Marvel Mystery Oil (MMO) as an additive to the engine oil. While I did follow his recommendation initially, I am reluctant to continue using Marvel Mystery Oil although I understand it may also be added at rate of 20% of engine oil and/or 2 ounces to 5 gallons of diesel fuel. Supposedly, the addition of MMO to diesel fuel will serve to increase compression, and act as a cleaner and lubricant. Do any of you concur (or disagree) with this mechanic's recommendation with respect to MMO use in an older diesel, and have you used MMO as a fuel and/or oil additive?

[Lepke]

The diesel sold today doesn't lube fuel components as well as older formulas. So anything that improves lubrication is probably good.

It's not going to change compression and depending on how it burns with either help or hurt the engine. Some home remedies cause more carbon buildup on cylinder components.
There are professional diesel additives that are proven to increase lubrication of fuel components, increase combustion, have biocides that kill bugs in the tank, decrease soot, etc. If you're going to buy something to add to your diesel and oil, maybe you should look at products with proven results.

[Calif.Ted]

I had a '75 International Harvester 345 cu. in gas engine that had a sticky hydraulic lifter, a little MMO cleared it in minutes. Don't think the amount ever approached 20%, less than 5 would be my guess.
For my 20 yo diesel I just use Valvetech fuel from the dock with a little cetane booster.

[Chayal]

I’ve broke loose several seized engines with MMO.

I use it on a regular in all my owned internal combustion engines.

There’s plenty of snake oils out there I’m sure...

Big fan of MMO, as well as sea foam

My old man used to use MMO as an additive in his DD15 semi, when he sold it, she was still running very strong with close to 1.7m on the clock. Long haul.

[Chayal]

I remember some old timers would add ATF to their tanks to help the lubricity in the fuel too.

[S/V Adeline]

In my years driving diesel trucks OTR we added ATF for the detergent quality, very illegal though (for dot applications)
I recommend using a proper gas or diesel additive

[Shrew]

MMO is great to squirt into the cylinders of any engine that has not been run in a very long time (years). Helps if the ring has decided to marry the cylinder after sitting for so long. squirt some in and wait a few days then turn over the engine. It has worked great. Typically used on old motorcycles, lawnmowers, snowblowers, etc but had success with a friends old Firebird back in the late 80's too.

[Compass790]

I wouldnt bother using anything in the engine oil.
It has it's additives in it to meet the API standard. Just change oil & filter as recommended in the manual.
I don't know MMO to be fair.

[a64pilot]

Originally Posted by Chayal

I remember some old timers would add ATF to their tanks to help the lubricity in the fuel too.

ATF is a high detergent oil, it will actually clean injectors, maybe not as good as some additives, but it really works.

Now I’m not normally a fan of additives as the best are usually snake oil, doing nothing but relieving you of money and the bad ones will actually cause damage.
However I’ve seen a few examples of MMO actually working, I’ve seen more than one Pratt & Whitney R-1340 engine that would stick valves if there wasn’t MMO in the oil.
I’ve also seen evidence that MMO is nothing but mineral spirits, some red dye and peppermint oil or something that smells good.

MMO was created God knows how long ago by the person who built the Marvel aircraft carburetor, I’m talking back in 1902 time frame Just as an example the Wright Bro’s first flew in 1903 I believe.

https://msacarbs.com/company/marvel-schebler-history/

Anyway MMO was created to keep the marvel carburetors clean, back in the 50’s Delta Airlines used to buy it in 55 gl drums.

MMO has never been a legal additive for aircraft, but I’d bet that a great many fly around with it in their oil.
Just don’t add too much, it does dilute oil and my opinion is it “cooks off” that is evaporates over time.

https://en.wikipedia.org/wiki/Marvel_Mystery_Oil


On edit, the Marvel carb is still built and widely available both new and overhauled. I would assume most high performance aircraft engines are now fuel injected, but if so thats a relatively recent thing.
I believe that as fuel injection isn’t subject to carburetor icing and I’d bet the Lawyers won’t let carbureted aircraft be built due to fear of lawsuits
https://www.aircraftspruce.com/catal..._10-4895-1.php

[boatpoker]

Snake oil ... Every refinery has already put appropriate additives in their fuels.
Unless you are phd. in oil chemistry you have no idea what is in there or what it is doing. Do you know more than the refieries ?

With over 22,000 hours in my log, the only time I had a problem was after beig talked into adding Marvel Mystery Oil. Within a few weeks the rubber grommets in my lift pump disolved. ... 1971 Perkins HT6-354 with 20,000hrs.

I won't be talked into Algaecide (algae simply canot grow in diesel) or any other additives again.

[S/V Adeline]

Refineries add the appropriate additives to meet or exceed EPA requirements. You will have a long fruitless search finding any EPA requirements that are specific to prolong engine life. I was working for a major US vehicle manufacturer in the early 90's, just after they rolled out their new strategy for 60k (4cyl), 80k (6cyl), and 100k (8cyl) mile engine life expectations. Appropriate API oil meets those expectation guidelines.
In a nutshell, they want you to purchase a new vehicle every 3-7 years, and have planned the engines to last that long before serious mechanical issues. This is why most *high mileage* oils are recommended after 100k miles.
And I'm old enough to remember when said companies bragged and promoted million mile vehicles.

[mvweebles]

For anyone who thinks oil formulations haven't evolved, spend a few minutes watching this YouTube of a guy who bench tests all sorts of stuff. He got a hold of a 70 year old can of Quaker State and compared to modern oil.

https://youtu.be/-zHlxeu_yuM

Its a good channel. Several seafoam tests.

Peter