The Cessna 120-140 Association Forum

The MMO container says you may add it to your OIL , up to 20% of the oil volume, so 1 qt in a 5 qt capacity. I'm wondering if anyone out there has tried this, also if they have flown with it. Just askin.

I recommend you do not try it. MMO is primarily a solvent. Adding 20% solvents to your engine oil then running at 70% power or so just doesn't seem right to me. Also, unless you're running you sump at the full 5 quarts, 20% would be less than a whole quart.

Back when I used to fly photos, from 9000 feet above the ground, I would get a little engine shutter and have to level off and cool down a little to finish my climb. Marvel oil cured the problem. I found it worked best in the fuel. I think I tried it in the oil first and noticed no difference.

Thanks Randy, I hope you were not affected by the Fires in CA.

X2 for adding it to the fuel. Since I've started adding it every 3rd - 4th fill, I have had zero fuel valve problems and borescope shows clean intake valves

I always use it as directed in the fuel. When I bought my 140 the previous owner who used it all the time said to use it or the plugs will be more prone to fouling with led deposits. My A&P said the same thing and uses it in his aircraft. I didn't buy into it after reading all the back and forth on the web. Then I started to have some cold misfires on plugs. Started using MMO in the fuel and the problem went away. I have also read that it can help the longevity of your fuel selector valve or help if it is a bit sticky. I have the original fuel selector valve and it works perfectly. Not sure that's science but MMO does no harm IMO. Wouldn't put it in my crankcase though.

How much do you add to a full tank for it to be effective?

8170 wrote: ↑Mon Sep 24, 2018 11:15 am How much do you add to a full tank for it to be effective?

4 oz. treats 10 gallons is what my bottle says

Thanks Randy