A question to an experienced mechanic engineer?

i'm working in a textile factory in a little city.and there we face a problem !!!and there is no expert to solve it.i really want to find a solution for it.and here is the problem...there is a screw compressor which we are supposed to change it's oil after 20 days but it makes it black at a really short time and we have tochange the oil after 2 days.what can bethe problem ?can anybody guide me?if you want more details mail me,thankyou in advance...