Well, let me start by saying that there are certainly alternatives! Everyone has their brand of choice. Mine so far (currently) is dinitrol because the range is better than waxoyl and their products are fairly easy to source.
I normally buy from eBay or here:
The DINITROL brand is one of the leading, worldwide operating suppliers of systems for bonding, sealing noise reduction, abrasion protection, corrosion prevention and other coatings, along with application equipment to the bus and railway industries. The products and application systems use the...
www.rust.co.uk
I wouldn't use the same stuff for the whole car, I would pick different products from their range to suit each area.
For simple coating of new parts I have used 4010 which is a high temp clear, it cures within an hour to a semi hard, satin finish. I have used this on new springs, shock absorbers and lower arms etc. I would not use it on old/already rusty parts because it doesn't penetrate very deeply, rather sits on the surface (fine for new smooth parts).
For that application I would spray on, two coats and call it quits.
I have also used their penetrating cavity wax (ML) in the bottoms of the rear wings, take the rear door (I know there are no doors, but you know what I mean) cards off and you can see right down to the inner sills, they sometimes rust there.
Dinitrol ML Penetrating Cavity Wax 500ml Aerosol Dinitrol ML Cavity Wax is a highly penetrating, water displacing rust prevention fluid. It penetrates into the finest cracks, forming a protective film once dry. It’s ideal to apply in doors, sills, bonnets, boot lids and other cavities. It leaves...
www.rust.co.uk
For body work I would first prepare the surface with a wirebrush in an angle grinder and brush paint with epoxy followed by a mix of stonechip and cavity wax, you will probably find the cavity in front of the rear spring pads is nice and crusty, thats a great area for cavity wax.
But like I said, there are hundreds of different products from various manufacturers. For me Dinitrol seems to be a fairly OEM choice that has done me well so far, there may be better, there are certainly worse!
also check out EM121 epoxy mastic.
