Originally Posted by cyccommute

I would say that it only melts minimally. There's not a lot of friction involved in the drivetrain. The wax may melt under pressure but I doubt that it's significant nor enough for the wax to move back into places where it has been forced out. It it flowed more, it wouldn't have the problem with water that it does.

This article details a Johns Hopkins study that was done on chains and chain efficiency with regards to friction. They found little friction in the drivetrain.