Steve I like the sound of it, I can even cure it in the oven in work

are you sure this wont wash of with petrol ???
We had the rep from PPG in the factory today but I missed him and couldn't pick his brains, We have aluminium coatings for plain steel, tinplate and aluminium that cure at 205C for 20 minutes so i'm pretty sure there are 205 litre drums of the stuff right under my nose !
I could spray my knackered cylinders with the stuff then leave it in the oven to heat cycle for a week, soon see if its going to discolour
But for £20 i'll use por20 as long as its not going to react to petrol