Undersealing/rustproofing

Ive seen articles where Bilt Hamber has come out on top, ones where it's Dinitrol, POR and other products.

Bilt Hamber if nothing else is very easy to use.
Looks and smells like cow st though.

It seems a lot better test than most, where I agree you get a different lot of results. Actually having tested it over a 3 year period to see which last and which has dried up and become useless, is more interesting than some who do a weeks accelerated testing and think it relevant.
Waxoyl was rated as great value, but was also judged to have lasted better than the others over the years and to show less rusted forming.

i've used the bilt hamber dark stuff in the chassis sections, its easy to apply as it comes with a lance and brass bit which sprays very finely. it gets everywhere while its thin and then sets hard, you can wipe it off with white spirit if it gets where you dont want it. personally i prefer the clean look underneath, so you can see whats going on rather than assume all is well under a dark covering.
its only been on a yr so i need to keep an eye on it, but my sunbeam lotus very rarely goes out in wet conditions and never sees road salt so i'm hoping the coating lasts a good few yrs