Grill , bumper and everything I use a pressure wash and degreased it with enging cleaner first. Scraped anywhere it was heavy grease or mud stuck to it. When it was all clean I used an Etching primer and rubber euro undercoating. I sold the truck but seen it last month and it is still clean. The guy washes it lots, we get lots of salt dumped on the road here, hard to keep vechicles clean here.