So i bought a pretty nice 2018 sierra slt premium plus with low miles at a good price last week in michigan. Well after getting it in the air i noticed that it has a lot of rust for an 18. Almost looks like the sand on the roads had sand blasted it. I want to clean everything and get the undercoating done. And possibly spray all the other parts that are not coated by the undercoating. Are there any good sprays to soak this down before pressure washing? Does anyone else have this amount of rust also?