Undersealing the car

[CarmeloLabadie]

I'm thinking of undersealing the car. There is a small amount of rust on the bottom the the door seals (next to the side skirts). I've had a read of the underseal instructions, and it says to remove all loose rust. Can I just put this stuff over the small pieces of paint (with rust at the end of it)? Does this make sense? I can take pics if necessary.

[Rostr02]

Pics would likely be helpful. I generally would say to use a wire brush and get all the loose rust away, then use steel wool if the area allows then paint with some sort of chassis paint. If you are in an area with road salt, or ocean salt spray I would use a product like wool wax and undercoat the whole thing in the fall. Does not smell the greatest and is messy of you do it on floor jacks in your garage, but works.

[Tyson]

On 10/25/2021 at 4:31 PM, CarmeloLabadie said:

I'm thinking of undersealing the car. There is a small amount of rust on the bottom the the door seals (next to the side skirts). I've had a read of the underseal instructions, and it says to remove all loose rust. Can I just put this stuff over the small pieces of paint (with rust at the end of it)? Does this make sense? I can take pics if necessary.

It’s all in the preparation and that’s where the bulk of the money goes if you pay someone to do it. If you don’t get rid of it, sealing over it will accelerate and compound the problem making the rust worse and having completely the opposite effect that you are trying to achieve. Completely clean and remove all the rust and any contaminants, before putting any kind of coat on the underside.

[Paul]

Waxoyl is better IMO, doesn't form a skin like underseal. I put it on an Escort RS when I had it new in 1990, found it via the RS owners club a few years ago and the underneath is like new still thanks to Waxoyl. Had my Supra done about ten years ago, could do with re-applying but has done well.