What's a good fuel for OS46AX break-in ?
Her's a pic. of OS Fuel instruction's per manual.
I did a search here, but I got more confused.
I just bought a gallon of Morgan Cool Power
for flying(15% N -17%oil ),I think the oil content is
correct from what I can get from their web site.
I also have a gallon of Hobbytown USA (10%N -18%oil).
That I use on my OS40LA Trainer.
Can I use either one of these fuel's for break-in or
should I get something else ?
Thank's....

Use the 10% Nitro/18% Castor.

Any major brand of two cycle RC fuel you will find in the states will be fine. The morgan/coolpower is fine. The HobbyTown fuel is relabeled Wildcat, which is also fine. The 10%-15% nitro range will suit that engine well. Don't need a special oil (fuel) for break-in with most glow engines. My only real suggestion is not to mix oil types over time, i.e. if you are using all castor, don't switch to all synthetic after a few gallons, etc. Just be sure to follow any other instructions OS provided for break-in such as prop size and initial mixture settings.

Been using nothing but CoolPower 15% for the past couple of years for new engines thru old with no problems.
Have not used the other but expect it would also be fine. Use whichever you expect to continue to use would be my recommendation.

I'd recommend the 10% over the 15% for break-in. The 10% has a tendency to run cooler. I also like to add extra castor as an added safety factor for those accidental short bursts of over-leaned runs. This is the way I break an engine in. I'm of the mind-set that the engine's first breaths of life will determine how well it runs after break-in, so I treat it conservatively at first.