Ok guys, list your opinions & experiences with this stuff- include (if applicable) the main inmprovement you noticed.

I'll start with mine: my previous car ('95 accord 4 cyl 5spd) i used it in the gas & oil & kept it till 220k miles when it still ran fine. Main improvements i noticed were less ticking from valves, generally quieter engine, less oil burning (it didn't burn much to begin with) in the gas: better MPG (about +2) less spark plug fouling, & just generally smoother driving.

I haven't used it yet in the 'Yota

 

My 3vze had a pronounced ticking noise that went beyond injector noise or normal valve tick. At 160K+ the ticking kind of came and went, but was present 85% of the time and sounded like a sticking lifter.

I thought about engine flushes and the like but didn't want to do anything too drastic that might dislodge a bunch of goo and clog my oil pump.

I had good results using MMO in a tired Ford 289 years ago and thought perhaps my sticking lifter could benefit from the same. I opted for a gradual approach, with my next oil change I added 5 quarts of Valvoline 10w30 and only 0.25 quarts of MMO. (My 3vze holds about 5 and 1/3 quarts total.)

After 600-700 miles, the sticking lifter had quieted dramatically. I have changed the oil after 2,500 miles twice now adding the meager 0.25 quarts of MMO each time, and I very seldomly hear any lifter ticking these days.

I view this as a bandaid fix, not the best solution. I hope to pull the heads and have them cleaned and rebuilt this summer which is a far better repair. However, I believe MMO helped clean some varnish and crud from an old engine and helped it run smoother.

Just one opinion.

 

I don`t know if I ever used this in a car engine.

I know it works great for air tools this was all I used till I started using aerokroil

 

My friend bought a 39 ford panel that was seized and had been sitting in a field for a while. we drained the "oil" if you would call what came out of it oil, and filled it up with some marvel. The next day, it turned over! sorry this doesn't really help i'm really bored, but it was a good story eh?

 

I use Seafoam in the gas tank, crank, and through the booster..Ive used it on my lancer, yota rodeo and even my girls honda and if you want to see or feel a difference..i would go with Seafoam. i use half can in crank with oil and other half in gas...next oil change i run it through the booster and maybe 6 months later i run it again...My girls honda was stuck on 70 miles with the pedal to the metal..after seafoam i hit 80-90 miles easy as cake...
I swear by seafoam. check out youtube for some vidz...hope this helps.

 

the only time ever used MMO was for air tools and as a penetrating fliud.
But then again I'm not much of an additive type of guy though.