Tru-Color Paint is some of the best on the market. This is the same paint I use on all of my models now, in my opinion it sprays as close to our beloved and missed Flo-quil paints. The paints spray nice from an airbrush at 28-35psi depending on your airbrush straight from the bottle. The paint does not require thinning, but can be thinned if you prefer. My recommendation is to buy a small container of the thinner and top the bottle off before spraying and it will work great. It is normal for bottles to be low from top, its due to the solvent thinner evaporation due to the type of bottles being used. It does not effect the paint in anyway, just top off with thinner, shake, and spray! When sprayed properly it leaves a nice finish that can be decaled right onto without clear coating. After Decaling we have a variety of different clear (Flat, Satin, Gloss) and many weathering colors to bring out the realism. Another great thing with this paint, multi-color paint schemes can be done in the same day, due to the solvent based nature of this paint, you can let it sit under a light bulb for about 30-60 minutes or similar heat source and you can then mask and spray your next color.
I will admit, at first I was skeptical of this paint as I always used FLO-QUIL for my railroad models, but after trying this paint, the results are excellent and I sold off my flo-quil supply. I really like how Tru-color has so many different freight car colors, it gives your train a realistic look with different shades, rather than every car being the same shade of box car brown,
Give Tru-Color a try!
To give an idea on amount needed for your project. I thin mine about 20% and from a 1oz bottle I can get 2 brass O scale Average Cars. A small Steam engine or diesel usually 1oz will get it done and larger steam I grab a 2oz bottle with some left over.