Hi mate
Waxoyl very good, used it many times before BUT...it can be awkward to spray without the correct gear. I have tried all different ways, best if you can beg/buy/borrow a small compressor and possibly an attachment like a "paraffin spray gun" (often part of the kit if you where to buy small diy compressor.
Your gonna need a lot of patience and various lengths of small bore nylon pneumatic pipe (6mm) for example. When you buy the waxoyl kt complete (bit pricy to be honest) they include what can only be described as a small nail thats been squashed flat along its length but leaving the head intact. Thats pushed into the end of said air pipe creating a fan effect as the waxoyl is sent down under pressure.
Its proper messy job mate, if you can find some waste land all the better although power for comp is an issue then. But nothing hard really about it, just need a small vessel that can be pressurised safely to only about 20psi if that, gallons of waxoyl, tube for running into sills from beneath through drain holes, a spray attachment for open areas like floor, you prob get the idea lol.
OR....if you cant be doing with all that, this id what I did but cant say if its better or worse than waxoyl.
Go to Screwfix, buy 20 quids worth of WD40, pop to motor factors and buy big arsed tin of grease, the more oily the better as there are many types. Jack car up and place on safe stands and then spend a half day painting oily grease EVERYWHERE you can see apart from bushes and brakes of course.
You'll prob have about 6 big tins of WD40, use that to spray down all sills/chassis legs/doors through drain holes/open boot and spay shed loads through access holes in carpet through into side of rear of car body right over rear wheel arches (open boot). This will go between skin of outer panel and lip of wheel arch and also drain into sills also.
Its pretty good stuff, used to fill it where I worked is WD40. I believe this method is just as good as using waxoyl although one a year (no biggie really) the car should be back on stands and given a once over re grease if any had come away etc.
All i would say is, maybe one of the MOT guys on here would advise better but prob best not to cover brake lines and fuel pipes too much as MOT man will not be able to check properly.
I did mine couple of years back and its been great, just as well with all the salt they throw on the roads every winter.
You may want to consider also, buying a big tin of underseal that has added waxoly for wheel arches right underneath. Gotta clean all the crud off first though but its worth it.
Hope all makes sense? I happen to think that one full day doing this is priceless since we love our cars, hence this forum
Good luck mate, anyone feel they can improve or add please feel free
