Underbody protection

[pcatterall]

My older (94) camper has just had to have quite a bit of new floor welded in, can't complain after 13 years though. Main problem seems to be water getting under the underseal and poor sealing between the floor and the 'chassis'.
Just been under my 'new' 2001 van to check her out. Things don't look too bad but there is evidence of surface rust starting. (no underseal has been applied)
Question is what if anything can/should be done to keep the dreaded rot away bearing in mind that some rust is evident.
Apply underseal? Use waxoil? Try to treat existing rust first with 'rust convertor'
Most grateful for your advice guys.

[madmark]

if you can get it up in the air i would use waxoil

[tranycamperman]

As madmark says, get it on a ramp or pit and get it waxoyled. Don't forget to inject it in side cross members and 'chassis rails' etc.

Whatever you do don't use underseal that leaves a rubberized coating on the bodywork, they do work well for a whille, but as soon as you get a pin hole in the skin, from say a stone chip, it lets the water in and quietly rots away untill the first thing you now is the mot man's telling you the vans failed on excessive corosion

[viper]

If only we could earth our vans to the road how different things would be