I’m going to paint my 1967 GTO with PPG brand code 9000, that is the blackest black currently on the market. I’m repainting it the original color. I own two black cars, what was I thinking?!
PPG brand code 9000 is straight black toner. Black toners tend to shift brown when let down. If you want a truer black, use PPG brand code 9835, GM paint code WA8555, which incorporates some dark blue to keep the brown shift to a minimum.
That may vary with different manufacturers of paint. I’ve only dealt heavily with PPG and Sherwin-Williams, but it was true with both.
Now you’re shooting a third? You’re a very sick person and should seek professional help. ;-)