In my GX CS4-i, the discharge from the bleed valve is water with a bit of white grease from the grease cup. The only time I've experienced a black discharge from a compressor was when an o-ring in my Shoebox disintegrated. That was messy!

Do you have an external filter between your CS4-i and your tank? If so, the filter may provide more information on the black discharge.

JackHughs
 
In my GX CS4-i, the discharge from the bleed valve is water with a bit of white grease from the grease cup. The only time I've experienced a black discharge from a compressor was when an o-ring in my Shoebox disintegrated. That was messy!

Do you have an external filter between your CS4-i and your tank? If so, the filter may provide more information on the black discharge.

JackHughs
I have just the CS4 not the i version. I do not have an external filter, I will be purchasing one soon. I do keep the bottle higher than the compressor to help water getting into the bottle.

I did figure that the greasy feeling in the water was from the grease cup lubrication.