I have been running auto fuel in my 150 and it was suggested to me to run MMO. I have been trying to keep some Avgas in there too so there is some lead to lubricate the valves but sometimes I just have Mogas. How much do you use? I had a guy that rebuilds cylinders tell me he uses a shot glass in each tank on a 120. How big are the tanks on a 120 about 12 gallons? Thanks

I use 4oz's per 10 gallons, not sure why but it works great and I notice a difference.

Anyone else?

I used it all the time back when I had a C-180. Then one time I filled a glass gallon jug with non-ethanol 87 auto gas and the proper amount of MMO. I mixed it well and left it sit for 7-10 days. All the MMO settled out into a glob on the bottom. That was it with MMO for me.

I have used MMO ever since lead fouling of the bottom plugs in my Cont C-145 in the C-170 about 14 years ago. I contacted the Superior Engine people when I first got my ACA High Country and they said it was OK to run it in my O-360. As MM stated use 4 oz/10 gal of gas. When it is above 50F I just dump it in the tanks prior to filling. Below 50F I mix it 50/50 in a container with gas, shake it well, and then put in tanks prior to fueling. I run no more than 50% 91 Oct unleaded car gas with 100LL and have never had a problem. We changed out the cylinders at 100 hrs on the Superior O-360 because of a factory recall and when we checked all of the valve stems had a very fine coating of oil and the valves showed absolutely no wear.
I have never had a fouled plug up to 100 hrs since I started using MMO. Before MMO use, at 20 hrs on the C-145 Cont, I had new plugs fail. Almost everyone I know with a Continental engine uses MMO for the same reason.

4oz/10 gal, shaken not stirred.

I had heard of it settling out also So I mixed up some in a glass container to see what happned, and it stayed in suspension. Go figure. Guess that's why they call it mystery oil

I'll try it again.

As HiC says, it does seem to put a coating on all parts it comes in contact with, which hopefully helps protect them. I don't generally keep my tanks full, so I have also been hopin that the residual coating would help preserve the fuel bladders.

I put the MMO in the tank then add the gas, mixing it up. Never showed any concentration of MMO when sumping.

Jaerl wrote:How big are the tanks on a 120 about 12 gallons?

Pretty much, 12.5 gallons to be exact.