I have not used this stuff but it looks like the ideal option for axle and other under-body corrosion protection. 96% zinc in the final coat is as close to metal on metal as it gets.

https://supply1.co.uk/zinga-galvani...MIrtum-qHX6AIViEHTCh1Sigr8EAQYAiABEgK_bPD_BwE

https://www.ebay.co.uk/itm/Zinga-Cold-Galvanising-Zinc-Paint-Primer-1kg/172425934480?epid=557301493&hash=item282562f690:gUAAOSwjY1ai~Qd