ORIGINAL: j.duncker
I have wandering the highways and byways of the US in a RV for a couple of years and by necessity have had to use a variety of fuels and although I usually stuck to 10% I too had to fiddle with the needle most times I changed brands.
I suspect the type of oil used changes the flow rate through the needle valve. I was flying 3d so max rpm was never an issue and I never bothered with the tach to check it.
That's what came to my mind. When it says 18% oil it's an oil blend and they can all be different from brand to brand. I use Power Master 15-18 and when I went to there 20-20 none of my engines liked it, the 20-20 has not only more nitro but a bit more castor oil. {from what I was told} I can change from brand to brand on some fuels and never notice a difference but then I can go to one brand and have to do a complete tune up on my engines. I know the brand and just don't use it. I'm lucky enough to always be able to get my fuel of choice and don't run into that problem too often. A couple of weeks ago I did borrow a tank of fuel from a friend and guess what it was????
