Originally Posted By: RRich
I just drained the fluid in my CC hydro unit after 215hrs. I can't believe how metallic it was.
I went through a similar experience over the last couple of weeks with a second-hand CC Z-Force ZTR with Hydrogear ZT-2800 hydros and 450 hours on the clock. According to the previous owner, the oil had been changed once at 100 hours.
I was experiencing cavitation (with accompanying loud noise and "mushy" operation) in the right side hydro when it got up to temperature. I checked the temperatures at the pumps on both sides with an IR thermometer, and the right side was getting MUCH hotter (usually ~10 degrees C hotter), so I decided to change the oil.
I changed it with Castrol 20w-50 and new filters. The oil I drained out of the right side hydro was BURNT (black), with metallic sheen. I thought I had done some real damage to the hydro. I ran it with the Castrol for about 5 hours, watching the temps closely. The temps improved, but the right side was always about 5-6 degrees C hotter than the left.
After the 5 hours, I changed the oil and filters again, this time with Mobil 1 15w-50. I have since checked the pump temps on each side frequently, and they are both always within 1-2 degrees of each other, and overall temperatures are down 7-8 degrees from when I bought the ZTR. I've put ~15 hours on the unit since the switch to M1, and the oil still looks good and operation is smooth, strong and quiet.
...as a side note: I determined later that the reason the oil burnt in the right side hydro was that the bracket to hold the bypass lever in place was not adjusted correctly, and it was slipping into bypass during operation of the mower. This overworked the pump, and therefore burnt the oil. I have since adjusted it, and everything is operating perfectly.
