Irrespective of dilution ratio, Life Color is not a good paint for airbrusing. It's really hard to paint with small spot. Also opacity is not best. But they are really nice with brush
In fact, I prefer it to Vallejo when it comes to airbrushing, though I don't know what specific ratio I use, I have yet to find one fault with spraying it. It has always worked flawlessly for me.
SoarinSukhoi,
you may just try 50:50 at first and see how it reacts, it depends a bit on your nozzle size and pressure your spraying at , but 50:50 might be a good starting point.
I go with approx. 60% Paint 40% thinner with Lifecolor and I use Tamiya X20A thinners. It sprays good for me but I find that it likes to be built up with thin coats. That's my 2 cents worth anyhow. Oh and it does hand brush nicely as well.
cheers,
FW190