Try Hammerite special metals primer, it specifically quotes galvanised. I
stripped and repainted a galvanised metal garage door a couple of years ago
and primed with ordinary metal primer but it started peeling off late last
year. Stripped and repainted using the Hammerite this spring, we shall see.
I have previously used this primer when repainting alloy wheels and had no
peeling or flaking even after a couple of winters. It has enormous coverage
so is very economical.
----- Original Message -----
> I have a new gas tank. It's galvanized metal.