My S60 D5 had O/S/R wheel heating up turned out to be caliper and flexi after a full rebuild of rear brakes it turned out to be one thing

 

A lot of brake caliper problems can be caused by failing to replace the brake fluid every two years or so. Brake fluid is very hydroscopic which causes the pistons to rust. Every new car I buy I ask the dealer after two years to replace the brake fluid, I usually get the reply
"Why?" I am astonished that dealers are not aware of this and that replacing the brake fluid is not part of a two year service.