Any ideas on the best type or brand of undercoating for my 99' Blazer? Also, what and what NOT to undercoat. I plan on power washing the underside first and giving it some good dry time.

 

There is a lot of choices out there everything from rubberized undercoatings to using truckbed liner also just painting the frame - all of whitch I have done in the past - One thing to be aware of is make sure frame is clean and no major rust is forming as it will still rust away under the coating - buff the areas well and use a rust deterant first. I've had good luck with rustolium and duplacolor products.

 

I was thinking of starting a thread, but will add to this one. I have a 2003 blazer with some surface rust on the frame. Is spray painting over the rust just fine? After washing of course. I don't want to be brushing and sanding. Should I use some primer first?

 

If you don't get rid of the rust before you paint it's just going to continue to rust. It's best to get off as much rust as possible and then apply a rust inhibitor like por15 or chassis saver. They aren't cheap but they are the best solution IMO.