Painting a galvanised chassis

I've bought a new galvanised chassis for my series 3 land rover, its shiny and I'm spraying it black put how do I prepare to prime it.

Some people say to vinegar the chassis and somebl say to use chemicals to help primer to stick.

There's lots of how to on the internet if you use your favourite search engine. Never done it myself so can't give an opinion on choice

Make sure you give it a really good scrub in degreaser and wash it off well, when dry use T wash and then use a good chassis coating system. Specifying one will cause some argument so you takes your pick of paint and primer. However up to that point is a given.

On my aged but sound galv chassis I used in several coats a whole can of rustoleum special metals primer for galvanised and non ferrous metals, it did seem a bit chalky, i dont expect to use that brand again, some research came up with phosperic acid which i regularly use as rust killer/ neutraliser as being a good mordant to use on galv,
i overpainted it with this from my local farm supplys

And then a good anti corrosion tractor enamel,
I also sprayed copious waxoyl into the insides,

I put vinegar on the battery tray as seen in the picture and under the has not been touched