Thanks everyone for your suggestions, I ran a gallon of castor blend through my heli when I first started and it turned my pipe all brown, then I switched to cool power and I have ran probably 8 gallons of that and I havent had the problem of the brown caking onto the pipe. I have been flying planks for many years and had never really gave the fuel any thought and the other day I was out showing an old timer the heli and he told me I really should run the castor blend fuel's, so I started to think about it and I wanted to know, so thanks everyone. I was a diesel mechanic until just a year ago when I broke my back and it made me unable to be one and I found out then that synthetic was always better then regular oil but when the old timer told me that I thought maybe he knew something I didn't.

Thanks again,
Jason