I've never heard of powdercoat coming off with petrol (Gasoline) or brake fluid. I got a frame coated last year (on my F2) and the coter asked me if it'd been previously powder-coated, I asked why, and he said they charge extra because they have to burn it off, and then sandblast the remains off.
I wasn't too keen at this prospect, so was happy that mine was just the rusty old factory paint job, plus a bit of rattle-can art from a PO. Two pack (2K) is great paint, but not a patch on powdercoating, and a lot more expensive when you add all the components required to do a good job. Cheers, Terry.