The engineers at CSF know cooling. So when it comes to keeping your power steering fluid temps in check as you push your E9X M3 hard on the street or track, the CSF PS Cooler is the obvious choice. While often overlooked, your power steering system can become quite annoying if it overheats. As power steering fluid boils it gets bubbles in the system leading to sloppy steering response and a noisy pump. On top of that, you will need to replace your power steering fluid if you let it overheat which is both annoying and an added cost.