Sabot, the absolute best thing I have found to assure absolutely NO oils are left is Brake Cleaner. Just make sure you don't get any on ANYTHING other than the steel. That stuff will really do a number on plastics and wood. Pretty darn cheap and much easier than most other degreasers and boiling methods. You can grab a can at pretty much any auto supply. It's what the stuff is designed for. Taking the oil off disc rotors before installation. Leaving the oil on will crystallize your pads.