You ought to be OK using MMO for fogging Joe. and for loosening rusty bolts and freeing locked up motors or equipment. Maybe not so good for mixing with motor crank case oil.

I got curious and googled MMO.
An NTSB report says that it is composed of 75% mineral oil, 24 % Stoddard solvent and 1% lard.

The MMO product safety data sheet lists it as:
60-100% mineral oil, 10-30% Stoddard solvent (white spirit),
Tricresyl phosphate 0.1-1.0%, Ortho Dichlorobenzene 0.1-1.0%,
and Para Dichlorobenzene <0.1%.
The last 2 being benzene compounds (in very small amounts)

With that much mineral oil thinning the motor oil, the crank ought to turn easier and faster. Is that good? I don't know.
imho with some car/truck engines already using 5w-30/40w oil further thinning might not be good. some solvents etch metal. I'm going to stay away from it, as there are cheaper ways to get mineral oil and Stoddard if I want to use them for something.

Spicy mustard........makes it smell like a barbecue when it burns......

I bought my 86 V with a Mercruiser 4.3l vortec motor that sat for a few years and it was stuck pretty good,, filled ea cyl with MMO . let it sit for a few weeks...... worked her gingerly to free... Purrs like a kitten now!

I'm telling you it's good for gas in your car Last time I fueled up I checked the mileage and got 37 mpg I never got that the most I got was mpg

I used to use it in my cars too. you would get much better gas milage after the 2nd or 3rd fill-up.. works.. however you can let your car sit for any periods of time or when you start it blows some smoke. I would imagine its from the oil/ gas separating?