So if you install quarter panels and leave it on, what do you do to the rest of the bare metal? Do you add extra primer to bring to the same thickness?Second that - it depends. I think the PPG paint handbook / notes I found said to test with lacquer thinner as well - if it rubs off black then strip it - if it stays fast and no black color comes off with LT then its a good base to leave it as it will have been applied on near virgin metal to stop rust and will keep it sealed. I used mostly goodmark metal due to availability in Canada and it all passed the LT test so I left it unless I had to spot weld that area or something then I removed it locally only. AMD stuff is generally better than goodmark so I would think its good - probably made in the same place - but test it.