I've used red, white, black, yellow with no troubles at all over the long term with 15% and 20%. I DID have a problem with grey in that it was only 2 days dry when I fueled up, found a tank leak. The grey wiped right off. On my corsair I used it to feather into the blue topside. Let it cure for a couple of weeks, no problem. Just had to give it time. I've also used red and blue with 40% on a 1/2a that held up pretty well, but its only had a gallon thru it so far. Might not do so well on the long term. My 1/2a planes dont normally last that long anyway.
Edwin