Done a bit of reading to understand the options and suggested thinning choices:-
Types of treatment read from the Before 'n' After website, based on whether oil, wax or grease based systems: -
Oils: Are more penetrative but evaporate quickly. The application usually needs to be renewed more regularly too.
Waxes: As the white spirit in the waxoyl evaporates the wax grips the surface. - According to Before 'n' After this is why Waxoyl works better than Dinitrol, particularly on rust they say. (I also believe the waxoyl can be very searching, getting into small crevices, whilst the white spirit is in it)
Greases: These use oil as the carrier. Dinitrol is a grease type. (I'm assuming others like Dinitrol because it can be thinned with oils and sprayed easily and sits like waxoyl on the treated surfaces but being a grease, if that is what it is, it can be washed or wiped off more easily)
I'm with Before 'n' After and believe Waxoyl is the best but I don't fully share their view that I need experts to apply it, though its clear if you don't have the time or the inclination then Before 'n' After sound like the type of place to get it done. I believe that when you care about your own vehicle you tend to be more thorough and go a little further in your efforts to look after it, well I do anyway.
My view is this; Waxoyl thinned with white spirit and applied liberally to the inside of the chassis and other box sections, if put on thoroughly and in good quantities can last for a long long time. I will however reapply in a couple of years time in anticipation that I wont need to do again after that. (I repaired my old 110 bulkhead and one application internally lasted as long as I kept it)
The external areas of the chassis will be painted by hand using Hammerite Under Seal (with added waxoyl) after good preparation. This will be thick and protective and I will compliment with some spray applied waxoyl in the areas the brush won't get to. High wear areas are simply touched up when needed over the years but I find this stuff stays put and works very well. I read that Before 'n' After have an additive to help make the waxoyl more resilient to abrasion and wear, because they apply waxoyl internally and externally it seems.
I wouldnt believe one word written by b4andater, his service is so good he did a guys D1 and not many years after it failed its mot on serious rot, front wings off and the pics showed the wax had not reached all areas and even the areas it had reached still rotted away, the wax guy did pay for all the repairs after a lenghty forum battle.
Waxoyl does work but needs reapplying biannually at a minimum pretty much the same as all chassis waxes, waxoyl like all std chassis waxes is old school and there are meant to be better products out there, though I still dont believe any product will last forever so will still need topping up.
The engine/hydraulic oil added into the chassis wax mix will give you decent creep and it will stay snotty whereas white spirit will evaporate, leaving just the waxoyl which over time will lift away from the chassis surface.
Underseal is and always has been crap of the highest order.
It has killed more cars than it has saved.
What happens is it gets a wound and water gets behind it then the serious rot starts and you will be none the wiser until it is to late, think plastic coated garden funriture anything powder coated that lives oitside.
Back to the waxoyl, my Fil bought a new Nissan Sunny in 89 and waxoyled it, he reapplied it a few times over the years and it still rotted out big time, though to be fair he did get 20 years out of it.
I have had personal experience of waxoyls lack of grip in std form as it gets blasted away by the water spray chucked up from the wheels.
The thing is no one really knows how good stuff really is unless they keep a vehicle for many years as did my Fil.
