I run all my glow engines with Power Master 15%. I run everythig from A 1/2A to the YS 1.40 sport with the same fuel. I have used 10% and it worked fine for me. I have only ran into A fuel problem with one brand of 20/20 four stroke fuel but that could have been A batch problem?? None of my engines would burn it very well.
I was taught to tune by one of the very best YS guys so I'm able to get away with maybe A little more then other pilots. If you can't get A four stroke to run correctly then bumping up the nitro really helps. Other then getting A four stroke to tune {idle} better and easier I have never seen any reason for all the extra nitro and cost.
That statement will open up A can of worms!!
When I invert an engine I don't use A glow driver either!! I may as well open up both cans!!
John, Directions??? That guy at the club is always better then directions!!! All 14 of them!!!