IME, i find z2 and z5 to have slightly different looks, with z2 having slightly better durability. I use one or the other, with 2 nonZFX'd layers immediately. I get 2 months of solid protection before i add another layer.
I like z5 better on darker paint, although I suspect there is little discernible difference
I use ZAIO as a base. Try ZAIO and 2-3 layers of 1000P if you have a chance.