Have gone thru 7 or 8 gallons of fuel mixed with Wally brand castor from the pharmacy, it says 100% pure, i hope i haven't messed up any engines ,, they all seem real happy!! Would love to see some research on " about as pure as castor comes", that would be a great thread !! I have heard about the degumming thing, don't know what it means, figured if it is good enough for me to drink ,, anyway i have seen no problems with my engines ,, mostly .25 to.46 size. One gallon of Omega 15% nitro with 8 oz of "pharmacy" castor.. just because it is easy to get ,, since we go to wal.. all the time.. I do have a quart of Sig castor and will try on the next gallon for a comparison..