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 AUTOFOLD MIRRORS - CSL TRUNK - CSL DIFFUSER - AA SPORT TUNE - AA PULLEYS - BILSTEIN PSS9s - AS 40% SSK
CF CSL RACE LIP - NAVI - BMW PERF CF STRUT BAR - BMW GROUP N MNTS - GRUPPE M CF INTAKE - SUPERSPRINT - UUC SS BRKLINES, TRANS MNTS, RTABs - 4.10 M-SPORT DIFF