Hi guys. I bought a new exmark 20hp , 48" HP last week. I have 8 hours on it total and I changed the oil and filter at 4.7 hrs. I love it...except it has started running wierd. The left side drive is very jerky when I try going slow, turning around or mowing close to trees , etc. I was thinking that it could just be me, since this is the first ztr I've owned. But I dont remember the demo unit doing this, and its just the left side. This afternoon, it started doing it real bad..I let go of the left handle and it just kept jerking forward with the handle oscillating along with it. I checked the hydraulic fluid, and it was a little low 1/2" below the cold level(before starting it) . I put in Mobil 1 15-50 wt to the proper level, hoping this was the problem (getting air bubbles or something) , but it didnt help. I guess I just need to take it to the dealer, but was hoping for some input from ya'll. BTW: Since there is no way to change the oil without making a mess (very poor design IMO) I'm wondering if some oil may have gotten on a belt. I mention this just to help troubleshoot. I wouldnt think it would affect the hydraulics...but I gotta lot to learn on this thing. Thanks for any input!