I've used Assos Chamois creme for years. Have also used Paceline's Butt'r and the German Sixtufit Gesass Creme and like the Assos the best. I believe it does have menthol in it, and that's probably why you got the Icy-hot feeling. I think it makes the Assos creme feel cooler than the others, which makes it nice especially in hot centuries. I put a generous amount on both the chamois and me on every ride.

Cheers! - RJ