I got some leather seats think of spraying them gray or black anybody ever done it? And what brand you use?

 

Check out VHT's website. I have used their spay dye on some motorcycle seats and it works awesome, but they were not leather.

 

SEM is by far the best stuff out there for dyeing. We dye seats in a lot of our cars at work. Honestly though, it's more just to get the color back in the leather more than anything else, and it's a temporary fix. Cracks will re-surface through the dye in no time. Also, the more dye you use, the harder the seats get, so I would go with as light of a coat as possible. Best bet is to take the seats out entirely; you can dye them in place, but be prepared to immediately wide overspray off of EVERYTHING inside the car.