Pretty darn good.... so far. It's not done though. I think you have it in you to take it up a notch. :fencing This thing operated in a dust bowl, but you have lots of areas where dust would accumulate that are dust free. Every bolt, rivet and angle where two plates meet is going to acquire dust. In many of those areas you have dark brown from a pin wash - this is good as a shadow, but over this add the dust, just make sure some of the brown is still visible. Also I would go over the lower portions of the tank with a VERY FRIGGIN THIN COAT of Tamiya Buff. Angle the Airbrush up from below so you get a natural feathering. This will hide some of your oil stains - this is good, because then add new stains on top. Think like Shrek, this is a complex thing - it has many layers! You could also add some dust colored streaks - very faint mind you, from all those rivets along the sides. Be gentle you don't want the thing to look like it had an accident in a flour factory.