Well, I never used a "CLAY BAR" before... but I gave it a try yesterday with the old Supra! This car sat OUTDOORS under an OAK TREE in the SUN, RAIN, SNOW, ICE, BIRD-SHLIT, and TREE SAP (from overhanging PINE) for a NUMBER of YEARS!!! (LOTSa neglect... :-? ) A couple washes since I got it...