I used RPM on some stuff on my daily driver and it didn`t hold up at all. It rusted like there wasn`t anything on it. I've seen that too if the coverage isn't good. I think when RPM first came out ECS stated you can wipe off the excess RPM right after application (i.e., while the part was still warm). The logic was that the RPM was already in the "pores" of the metal and wiping off the excess did not remove the RPM in the pores. I tried that and it seemed to provide spotty protection. Now I just apply it and let it be - it's worked fairly well for me.
1968 Charger R/T, 440 Auto, GG1;
1969 Super Bee, 383, 4-speed, T5;
1969.5 Road Runner, 440-6, 4-speed, 96;
1970 Duster 340, 4-speed, EV2;
1970 Charger R/T SE, 440 (496), Auto, EB3;
1970 Dart Swinger 340 (416), 4-speed, EV2;
1970 Corvette coupe, LS5, 4-speed, Daytona yellow;
2000 Corvette coupe, LS1, 6-speed, Twin Turbo, Torch red.
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