I have had very good durability out of C2V3 as a stand alone when I prepped the paint like for a coating beforehand. I have not use it as a topper for anything. C2V3 is not really recommended on top of CSL. I don't think they recommend topping CSL with anything. C2V3 was designed originally as a topper for C1 before the EXO products came out. C2V3 will last quite a while on top of C1 also.