Hi,
a very big european magazine has tested a lot of different waxes and greases with which the car and it´s cavities can be protected against rust.
There were some "rules of thumb" which may be useful:

- a wax is suitable for new, smooth, not so much rusted surfaces.
- a wax relies on a solvent to aid the "diffusion" into corners etc. But once the solvent is gone, generally it will not "be active" any more. Cracks can be attacked by water again, f.e.
- waxes seem to differ a lot! by the amount of solvent. The test-boxes had been weighted and there were some which only were 4gr heavier than without any application. The best waxes were around 50gr. This, given all of them were applied by the same technique. Thumb of rules says the more the better.
- waxes are very easy to use.
- a good "brand" is no guarantee for good result. (Waxoil is ok (first place after the waxes), Fluid film too - but both "2k", Dinol is fine too. Holts is ok, and some more I cannot remember.

- all the first places were taken by the greases. The one that came out second was the MikeSanders (first by a margin was a professional system which cost a lot).
- the grease is a bit cumbersome to apply because it has to be heated to water boiling point to get it liquid and through a special air gun (the one which applies pressure to the bottle rather than a venturi-system).
- the grease will "wake up" when it get´s warm and start to crawl into rust. (Edit: I have smeared it to the backside of my RRC lower tailgate 1/2 year ago and now it managed to cover 1-2" of "travel" on the visual face of the tailgate. So over the time the grease will get to places not first coverd. That way it can "heal" defects of it´s coverage by time again - very contrary to wax.
- grease has slight difficulties to stick to smooth surfaces, it tends to slide off. That´s why waxes are ok for newish steel surfaces.

I live in Quebec, anyone will tell you we use more road salt here than anywhere else on earth, you can get great engines at the scrapyards because vehicules rust out in less than ten years. WAX IS USELESS!!! Use the oiliest, greasiest undercoating you can find. Clean the underside of the vehicule every summer with a heated pressure washer. Reapply rust proofing EVERY SUMMER, generously while the warm weather allows it to work into cracks. If the grease doesnt come out around your door handles and between body panels you didnt use enough. You have to drill holes to get in all the spaces on a vehicule.

I must admit that I agree with BigBlue Toy. I've been an advocate of Waxoyl in the past. The two door Range Rover I am working on at the moment was fully wax protected and in many areas (including closed box sections) it has cracked and flaked off allowing rust to spread. In contrast, any area in the viscinity of an oil leak is still pristine under all the goo.

Wax has its place as it dries fairly clean and it doesn't smell, but when the rebuild is done I'll be regularly spraying clean engine oil underneath and into every closed section I can get to - including the frame.

Why clean engine oil?

Why clean engine oil?

don't you have a cage to finish?:p I want to see the end result.

Why clean engine oil?

Used stuff has acids and other goodness in it that can eat paint.

My own Land-Cruiser rustproofing measures are a mix of chainsaw bar oil, a tube of wheelbearing grease, a wax toilet seal ring, and some fluid film, all melted in a big pot on a camp stove, mixed well, then applied with a Shutz gun.

I think a cheap alternative to use could be the grease that is used to protect steel ropes.
Places to find this grease I can think of are cable cars, cranes (at construction sites) etc.

It´s properties (I think it has) make it worth a thought. And because it´s non sophisticated stuff it´s ought to be cheap.
I think a few guys over here used it.
I, me landybehr, will use that MikeSanders grease because it is so readily available for me and it´s truly tested.

don't you have a cage to finish?:p I want to see the end result.

I actually just finished painting my drag link so that I can drive it out of my garage and take it over to my buddy Maxx's house so he can finish the cage. I just don't have the time, mad skillz, or motivation to finish it on my own time:flipoff2:

Used stuff has acids and other goodness in it that can eat paint.

My own Land-Cruiser rustproofing measures are a mix of chainsaw bar oil, a tube of wheelbearing grease, a wax toilet seal ring, and some fluid film, all melted in a big pot on a camp stove, mixed well, then applied with a Shutz gun.

A toilet seal ring!!!! WTF!!!! Thats hilarious! that mixture must reek like Fort MacMurray!!! The chainsaw oil is great stuff, use the summer grade , it’s thicker and stickier. The most important part of rustproofing if the ANNUAL cleaning and reapplication. Dont think ’’I rustproofed it when I got it, it should be good for a couple years’’ Its not! every year, when its still warm out.