There have been countless claims of the benefits of MMO for decades.  None of them have been substantiated by scientific study.  I wouldn't put it in my airplane.

Walter

be  careful..as far as I know Avblend is the only FAA approved additive for oil.  If you insist on using the Marvel I would treat it as experimental.  Besides, if I knew I had sticking valves I wouldn't trust magic additives to cure it (Marvel might help prevent sticking but there is no proof of this in studies.)  Sticking valves are serious business, if not corrected you can trash a cylinder/engine real quick.  Pull the jugs and inspect the valve stems, guides,etc. to be sure!  Steve VW

I use it in one tank of gas about every 100 hours (between inspections).  I have found that the compressions are better if I use it close to the time of the inspection.  I have one cylinder that has been a problem, but fly 5 hours worth of fuel (one tank) with MMO and bingo, it is as good as the others.  This is on an IO-520 with fuel injection.  I have not seen any negatives from using MMO, only positive effects.  It sure is a lot cheaper than AVBLEND.

I use MMO in all my planes. I won't use anything else. AvBlend is expensive and I can't tell it works. As for MMO I use it in my oil and and fuel. I a high time engine in one plane and stuck a valve. Started using MMO and the old gal is still flying and doing great. Yep I also use in in my old tractor as well as my 2004 GMC. SO, if there is someone that says don't use it well then that is ok. THey are right that it isn't FAA approved. That is why it is much cheeper to use as the Government hasn't stuck there nose in it and created 6 mile long paper work and lots of cost to manufacturer. So, Good luck and I do believe in it and use it in mowers and everything I have. VERY GOOD STUFF>
Happy Flying.

Was having some performance problems with my 70's model 172. Everything checked out  ok and we narrowed it down to possibly a sticking valve -I added some to the gas and oil and performance is now back.

Cessnadon  You are right I never found a overhaul to a engine problem  to be repaired from a can. If you have a engine problem FIX it.You'll loose everything to take off with someday with a dead engine. Is your aircraft only worth the price of a can of additive.What else will you do to save Money. I won't buy that Plane.  ANGELA

out of a can problem solver. The next time you are getting aboard an aircraft say 15 people let the pilot say she's had a valve thats been sticking but  I'll add a can of this stuff and all will be ok. Now you'll have lots of room for luggage. passengers moved elsewhere. what causes your engine to need it and mine not?If you like it use it. I don't. proper mixture and  proper plugs usually corrects these things.

I just saw your entry. Can you tell me where you obtain MMO in UK, please?