Okay my owner's manual is not really very clear on if I need to do anything about this and not fact it doesn't even mention it. But, the bi-speed turn gearbox (I guess that's how I'd describe it). I noticed it has what appears to be a drain plug I do not see a fill point. Is it part of the front axle assembly or the main hydraulic assembly so should I drain it? is question 1 and question 2 is does it get filled automatically from the rest of the system? Or should I just leave it alone it's entirely separate?