PPG clearcoat?

Thinner???? Not really, just don't think 5 sprayable quarts are enough to put on 3 good coats....If you wetsand and buff, not just nib sand, you'll be losing a coat... The 661 is 2-1 or 6qts sprayable, that should do the job.. I have alot of jobs out there with the 661. It's a nice clear also, but after using the 630 it's my choice. 661 is acrylic urethane, 630 is polyurethane, like DCU2002

Bob