what brand and percentage of thinner do you guys normally use for airbrushing? just wondering

Automotive Paint (BASFrefinish) and its respective Reducer mixed 2-1

Uhmm. I use a Paasche H for large work and a VL for detail work. (would like a set of Iwata airbrushes, but for now, the trusty old Paasche models will do) Really large stuff I use a DeVilbiss HVLP touch-up gun.

In both cases the paint is mixed and thinned to the consistancy of whole milk and shot with a 10 psi line pressure. As to the brand of thinner...I use different ones based on the type of paint being applied (i.e., read the back of the paint can the paint maker will tell you what to thin it with and by how much.) Regardless of paint type, what goes in the color cup looks about the consistancy of milk. That gives you the best control range without rediculously high line pressures.