My dad got 4 x 5L pails of PPG white epoxy primer from a guy from work, he gave it to me.. just wondering if this is what guys are using once they are done the metal work on the car. Also the expiry date on it says: 04/2006 is this still okay? Or is it junk now?

Is it DPLF? If it is, be sure to use the 401 catalyst which requires an induction period. The 402 is garbage and will allow the DPLF to wipe off with reducer, not good. You should be okay if the paint hasn't ever froze. Don't however use old catalyst.

Jerry