It's a "Mystery" to me.....I use it in air tools. Others have said it does a good job for that. They're still in business so I guess no one has sued them yet.....If Im not mistaken, this stuff was around before Automatic transmissions.......BobG in VA
Kubota B2710, IH TD6-62 dozer with Drott 4n1 bucket loader
Marvel Mystery Oil has been thoroughly discussed here on TBN several times. It is not ATF but mostly mineral spirits, chlorinated hydrocarbons, and napthenic hydrocarbons. The thread listed below has several links to MMO's actual specifications.
Use the forum Search function and you will find several threads of over 100 posts each discussing MMO. Here is one of the longer ones.