oem spring are going to be powder coated. which are much better and stronger paint protection than any basic rattle can Rust-oleum . I'd just make sure you have decent bottom rubber spring pads. When the spring pads wear through the metal and touches the aluminum it can exacerbate premature failure. But stress is the main culprit.
OE CSL WHEELS - OE CSL BRAKES - OE AUTOFLD MIRRORS - CSL TRUNK - CSL DIFFUSER - AA TUNE - AA PULLEYS - AS 40% SSK - BILSTEIN PSS9s
CF CSL LIP - NAVI - BMWPERF CF STRUT BAR - BMW GROUP N MNTS - GRUPPE M CF INTAKE - SUPERSPRINT - UUC BRKLINES, TRANS, RTABs - H&R SWAYS - 4.10 M-SPORT DIFF