Anyone used Waxoyl on a 308gt4 to prevent rust?

I wouldn't recommend it on external sections. Use it inside the box sections by all means. I've got a 30 year old car, too (not F-car) and I tried Waxoyl but changed to an upmarket brand later.

Teroson do a very good set of different waxes for inside box sections. Depending on the expected temperatures (I live in South of France at the mo.) you can choose a wax which isn't going to go runny at 40°C!

For external, use underbody protection. Again, Teroson do one that you can mix body colour paint with and which is over-paintable, too. This dries but remains flexible and is much preferable to a sticky wax which will wear off and which will attract all sorts of muck.

For the inner box sections, give them a good blast out with a compressed air gun first and, if possible, get in them with some pipe brushes before doing the wax bit.

Treat yourself to a decent underbody spray gun. They're not expensive (often on eBay) and should come with a spray nozzle tube extension for box sections and a normal jet for underbody sealant. I tried using the plastic Waxoyl sh**te sprayer which costs about the same as a proper spraygun and it just blew up (cracked) in my face - yes, literally!

 

Also look at the Dinitrol products range or there's the POR15 option (www.frost.co.uk)

 

Yep, I'd go along with Dinitrol too! Believe me, owning a 1976 Ferric Oxide gives you some rust experience which I hope will never happen to my F-car!

F.A.R.T. is also a good place to go. (Frost Auto Restoration Techniques)

 

I did my rocker panels and the inside of the rear fenders under the side windows on my GT4 using a homebrew Waxoyl. When I had my interior out I looked closely inside the area under the side windows and found mostly bare metal (never primed or painted). The rocker panels were the same. As a side note, although the rockers appear to be a box section there is a inner bulkhead that actually makes it more of a 2 triangle type section. Treating only one part won't provide protection. The GT4 parts manual diagram will help you visualize the structure.

http://home.metroweb.co.za/~pdoug/tips_and_recipes.htm
I made up a brew something like this except I melted the wax into mineral spirits/mineral oil on a hotplate. I did this outdoors with low heat, about hot bath water temp. I also sprayed it with a garden sprayer at the same temp which let it get into creavices before the mixture cools enough for the wax to solidify. Make sure to throughly clean the areas to be treated, vacuum out dust, dirt, loose rust were possible and blow out with compressed air. Make sure that your drain holes are clear as well.

WARNING, this stuff will drip out for days or weeks so don't park the car where you don't want wax and oil. It will also drip out months later if the sun heats the sheetmetal enough to soften the wax.

I found that the area just under the side window (by rear seat) tends to rust on GT4s because moisture in the air condenses on the inside surface of the fender. Also water draining off of the engine cover (at the rear window) tends to run along the bottom of the sheet metal that forms the flat interior area either side of the rear window. This leads to rust around the rear window/seat area. The structure around the rear fender, rear engine bulkhead and inner wheel wells is made up of multiple flat sheet metal panels spot welded (and sometimes not) together. The seams are then covered with a seam sealer. Water will get into this joint and then work it's way along the joint rusting everything in it's path. The seam sealer hides all this so I would recommend trying to remove some of the sealer. If there is rust under it the sealer will come off like a long piece of rope. Needless to say the fiberglass fender liners need to be out for better access. The doubler that is spot welded to the wheel opening in the fender is another area to clean and treat.

Photo shows wax in the rocker panel access inside the front wheel well, AC hoses run through here.

I hope this helps and I am glad to see that your interested in preserving the car instead of just selling it off after a couple of years.
Mike
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Mike, it sure looks like you got "excited" on your car.

 

My GT4 isn't rustproofed. I've worked on a GT4 that had been undersealed and it wasn't a pleasant experience. It smelt really bad and I got covered in gunk. Whenever I work on mine I always spray any exposed metal bits I come across with a light oil.

 

I have go some experience on my '75 gt-4. Rust in the places mentioned above plus in the trunk. Especially the deep side pockets in the trunk ("boot" to you limeys) behind the wheel wells. I actually dont think spraying wax over rusted areas will be of any help. Rust is hydroscopic and attracts water, and wax over the top of it will simply prevent it from evaporating out as quickly as it would otherwise.
The strategy I use is to scape out and power wire brush the rust spots as much as possible, preferably back to shiny steel, and then brush/spray on a rust converter/filler (usually a phosphoric acid which converts the rust to iron phosphate). Let it dry then apply red lead primer over the top of it. A top coat of Rustoleum (paint with "fish oil") completes the job for inner panels.
Rotted out spots get a thorough cleaning and grinding, and then get a aluminum patch expoxied over them, plus the above mentioned paint componets. The unprotected steel doubler plates, like in the rear fender liners are the pits. Grind small hole into the innner doubler, scrap out the rust as best you can, then skirt in liberal quanitities of rust converter, followed by red lead paint out of a aerosol can.

Martin Jansen
Yellow '75 gt-4 "tweety"
So California.

 

In commercial aviation where aluminum-to-steel and on pure aluminum areas the standard used to be LPS 3. Dinotrol has taken over as the prefered method as it is less waxy/messy, does not wipe/wash off, and penetrates into crevaces better.