I've noticed that the front wheels of my Z can easily get a thin layer of black dust while the rear wheels are still clean. Is this normal? If not, could this be caused by some oil leaking in the front area?

 

Probably because the front brakes do most of the stopping. They probably just throw off that more brake dust.

 

That's just your front brake pads, as they stop your car they wear slightly causing dust to gather on your rims. Your front breaks to most of the work compared to the rear that's why you see more of the dust on the front. And with this particular car it seems to happen much more readily because of the type of pads I presume.. Just hours after cleaning your car you will notice it back again.

D Monte

 

It's normal. Just like other said, front wheel do most of the braking job. We all have the same problem and they are annoying. Look like the pad is a little too soft, but stopping the car great though. I am looking for one with less break dust for replacement soon, but also don't want to compromise on breaking performance.