Anyone recommend Marvel Mystery Oil?

[Skuza]

I started using it on a 95 Ram we have had around for a few years. It never always got the proper oil changes on time and years later I’m trying to clean up some of the sludge. Seems to be running smoother and quieter. It won’t hurt anything and for $7-10 it’s innocent. If you have something new I would say not needed. Just do regular oil changes with quality oil. Marvel has recently released a “synthetic” version to probably try and enter the newer engine scene.

 

[blaster]

If you decide to add this to the crankcase don’t run it all the time. Put it in a few hours before the oil change. It waters down the oil and you need thick oil in a marine engine.

 

[Scott215]

It's recommended that I use semi-synthetic for my boat per MerCruiser so that's what I use I don't have anything to my oil just fuel, thanks Highslice

 

[Sprint27c]

I put it in the same mental category as Seafoam. Enough people swear by them that I'm open minded but I've also never used either...Probably snake oil.

Two first-hand stories of Seafoam.

First: was about a decade ago - riding HD motorcycles 1,300 miles to the Sturgis Rally. My wife at the time had a small 883 Sportster and had to run it almost wide open to keep up on the open highways and the oil temp was right near the upper limit. Also the small gas tank meant we were stopping quite often. At one gas station I bought a couple cans of Seafoam to see if it would help anything performance or mileage. Was a great experiment as we would run SF for a tank and then the next without. Result: absolutely no difference. Same power, same mileage, same oil temps.

Second: a friend had a small skiff down in the Bahamas with probably a 10 yr. old Merc 200 or so 4 stroke outboard. After setting idle for a summer we went down to use it and it would barely run - maybe 50% power. After some checking looked like the inside of the old fuel line came apart and crud went all through the motor including the injectors. We limped it for probably an hour to the nearest mechanic who only then informed us it would be a week before he could get to it. He sorta shrugged his shoulders and said "you could always try Seafoam!" I was a bit beside myself because we had at least another hour back home in deteriorating weather.

Undeterred my friend poured the Seafoam in and away we went. No difference for about 15 minutes then all of a sudden the damn thing came to life and ran like new. Without question the SF somehow cleaned out the debris. I absolutely wouldn't have believed it if I didn't see it myself..

So - not quite snake oil but as with all things use it for the intended purpose.

 

[scoflaw]

Exactly my experience. Seafoam is a cleaner and is excellent at decarbing