2003 W209 CLK, 2005 R171 SLK, Volvo XC40 P8 Twin Motor Pro EV
When we bought our 124 around 11 years ago it went through the same process with a similar Dinitrol outfit close to us. I think it was around £400. Money well spent. The underside looks just as good today and there has been no corrosion on the body panels. Eventually some wears off in the high impact areas under the wheel arches but easily replaced from the 500ml cans.
I read 10 litres. Let’s assume this is twice the density of water, so that would be 20kgs, or about a third of a tank of fuel or a quarter of a driver?
I’ve used dinitrol 4941 as a protectant for about 6 years on various cars, they’ve moved to aerosols from tins for the smaller quantities but it gives a very resilient and even finish
It’s not cheap however!
Considering the labour, the company in the PH link is doing a good job at a great price