500, 472, 425, 368 Discussion, Marvel Mystery Oil in Cadillac Engine Technical Discussion; Is This Stuff Good?....is It Worth They Money.....74 Eldo...can It Damage An Older Engine If I Accidently Used To Much........
it's pretty good stuff. it can do wonders for clogged lifters that tap. i have used a mixture of MMO and auto tranny fluid in and engine to get the lifters to quit tapping and it worked very well. plus it can be used for just about anything else that you would use a light oil for. it is also good in air tools
MMO is pretty much recomended for older engines. it is basically a high dtergent oil that will clean the gunk better than normal oil.
as far as damging your engine goes as long as you don't run like half motor oil and half MMO you should be okay. the oil itself wouldn't hurt anything but if you have too much of it mixed in the oil mixture might not stand up to heat as well.
Marvel Mystery Oil has been around for perhaps 70 years. Many years ago I spun a rod bearing in a 1969 Saab 96 V-4 at 176,000 mi.
I found an engine, that was laying under a tarp in a Saab nuts back yard. It was siezed up solid. I bough it for $5.00 and put it in the trunk of a rented Dodge Polara vintage 1975. I proceeded to fill every orifice of the V-4 with Marvel Mystery oil. The next morning I was able to turn it over with a prybar on the ring gear. Within a couple of hours it turned over freely enough to justify the transplant. After it was installed, I towed it around behind the Dodge for 5 miles with the plugs out. I then changed the oil, put in the spark plugs. It started up, and ran well for 70,000 mi until the body gave out.
Traditionally it was used alot with flathead engines that has a lot of valve guide problems and as a pickeling agent for long term storage.
I think that times have changed, and that there is no longer a need with the excellent motor oils available.
Where did you put the Mystery oil, in the gas tank or crankcase? If you think you put too much in the crankcase, just change the oil. I have seen old powerboats that had so much of it in the fuel, that you could smell it in the exhaust, and it did not cause a problem.
Thats all I know about Marvel Mystery Oil maybe less.
Lots and lots of people swear by the stuff.
I love the smelly stuff myself
usually ran it in the gasoline and like the previous post have used to to free up lawnmower engines that I got during spring cleanup ....that were out to the trash.
I like the stuff. While in my caddy I don't use it very often. I used it all the time in my old RX7 and that engine lived 20,000 miles longer than the typical life of a rotary. Not saying it helped but I won't say it didn't.
MMM is great to put in an engine that's been sitting a while. I usually put it in my snowblower for summer storage: drain the tank/run until empty, pour a little bit in and pull the cord to circulate the oil throughout the engine. In the fall I pour a full tank of ffresh gas in and it starts on the first pull.
For the car, I pour some in the spark plug holes during storage.
9 years ago, I bought a 77 coupe de ville with 57,000 miles on it from an old lady. Her husband waxed it all the time and kept it in the garage, but they seldom changed the oil. The lifters tapped. I ran 4 quarts of oil and one quart of Marvel Mystery Oil in it for 1,000 miles, changed it and refilled it the same way for several changes until the lifters were finally all quiet. It took a while, but now one may tap a little bit when cold, but that's it. Dumping a good helping of MMO down the carb, and then in the gas tank always smoothed any carbeurated engine I had, and even made my fuel injected Dodge Durango run a tad smoother. Upper Cylinder Lubrication is what it says on the bottle. I think they even make a product specifically for use in gasoline.
I was first turned on to mystery oil many years ago (about 30) by an old timer who worked on cars during the 1930's through the 1950's. He swore by it, and used it all the time. Then I started using it, I put it into numerous 472/500 engines without any problems (smells good too). It seems to keep everything cleaner inside the engine. I used about 16 ounces at each oil change.
I had a 1984 Olds 98 with a nice 307 that has about 140k on it. For some strange reason I decided to put this stull in my car. This stuff brought all the build-up and trash from the top of the engine to the bottom where it clogged the drain holes in the valley and caused no oil no to be able to drain back to the pan, anyone care to guess what happened from there? Well let me tell you, I spun 2 bearings on the crank. So, there is my story.