Heat the bleeder screws with a Propane torch and touch a candle to the bleeder while it's hot. The paraffin will do a good job of loosening the thread, and it won't make it past the tapered seat of the screw to contaminate the fluid. Also, use a 6-point deep socket and a ratchet on the bleeder screw instead of a wrench.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!