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Underseal advice.

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  • [Corsa B 1993-2000] Underseal advice.

    Just a quick one, next weekend I have a chance to underseal my car. Any tips?

    I was just going to take a drill with a wire brush attachment to everything then brush over with underseal/waxoil

  • #2
    Just try and clean off as much as you can first, then just cover everything in waxoyl it's great stuff I have a big tin of it and barely used much, you can thin it down and spray it on or paint it on with a brush (obviously inconvenient if doing whole underside)


    • #3
      I have a big can and some brushes, going to do it with a few mates on a ramp so shouldn't be too bad .

      As for the factory underseal I don't need to get rid of that? Just rub it down a little?


      • #4
        If you want to do it properly buy some Dinitrol rust treatment and some Ronseal no rust.

        Use an angle grinder and cordless drill both with brass wheel attachments to get off the worst.
        Then treat with Dinitrol (it's like Kurust except much better)
        Then paint with Ronseal no rust
        Then when dry underseal over
        Only need to do it with the rusty areas

        I undersealed over the rusty areas after i sanded them down the last time and it came back a few months later. Underseal is good at protecting good metal but does very little to hold back rust

        This was about 8 months after undersealing with just sanding down the rust and using underseal


        • #5
          Okay mate that's great advice thanks! Yeah it seems the underseal has worn off in that picture! I'll have a look at those products thanks


          • #6
            As above - the Dinitrol is much better. They also do a spray on underbody wax that is very good and easy to use. (Buy it from their ebay sale rather than direct from their website - it's cheaper that way.) Dinitrol 4941 is what you're after.

            Waxoil is useless - don't waste you time on it. It won't penetrate into the metal enough so rust forms underneath it and it washes off too easily.

            If you want to do it an easy and cheap way to kill patches of rust then remove the surface crusty bits and work so cheap grease into the rust. It soaks into the rust and denies oxygen to the metal so it stops the rust dead. It also seeps so works very well. EG on my Viva the floorpan down the middle of the car behind the engine is solid purely due to the engine leaking oil which has soaked into the metal. (This is no good is you are worried what the underside looks like as it makes a right mess and you can't then spray over with anything else - but for quickly and easily stopping corrosion where it breaks out it's the doggies danglies.)

            Original underseal - do you remove it or not? Hard to say as on many cars there is already corrosion beneath it as once it gets a small bit of damage water seeps underneath it and rust begins but you can't see it. I'd check a few areas close to where there is visible rust and see what's beneath the underseal - if it looks good then leave well alone.
            1972 Viva restoration thread -


            • #7
              Great advice thanks ! I'll put these tips to use next weekend!

              When I was under the car last week I noticed I'm quite lucky with how little rust I have for the age, the main parts are rear beam and chassis rails and behind the jacking points at the front

              Also is the dinitrol fast drying? So I could treat the rust and go over it with the ronseal in a morning?
              Last edited by Sam_Sri; 28-09-2013, 07:15 PM.


              • #8
                The rust treatment is pretty fast to dry off - two coats and providing the weather is reasonably warm you can paint the same day. It depends on are area covered and scale of the rust - yours should be pretty straightforward in a morning. (So long as you begin early enough!)
                1972 Viva restoration thread -


                • #9
                  Thanks Taurus!

                  Anyone know if 750ml of the ronseal will be enough for the bottom of the car? And where's the best place to get it?


                  • #10
                    You only need to dinitrol and ronseal the rusty areas dude so should be enough depending on how much rust you have. I'd do that then just underseal them once dry and the rest


                    • #11
                      Cheers pal :thumbup: