I'm not currently using anything. I use different vehicles for topicals, buy usually will use a little dmso, ethanol, and something like pg, peg or transcutol. It's stable up to 50c, I don't know about 60. RU is highly soluble though without heat in ethanolHuichem. I've held off RU until now, other aa's (duta, daro, apa, enza, bica, abi) hit me, so i think i might do a n=1...
what's your vehicle? do you know if it's heat stable? (interesting what disolves in butlyene glycol at 60c on mag stir)