These calipers don't appear to have dust boots, so as the brake pads wear the pistons get exposed to the elements. Before pressing the pistons back into the caliper I'll clean them with purple stuff, water, and an appropriate brush. Then I'll flush the brake fuid. At 15k miles the brake pads are shot and will be replaced at the same time as my front tire. A new PR3 is in the mail.
-RC