Oil and Filter on Gravely ZTR Hydraulics

[TBone]

The owners manual specifies 15-50 synthetic (motor) oil in my PM34Z mower in the hydraulic drive system. I discovered that my dealer filled mine with 15-40 NON SYNTHETIC oil (and the cheapest stuff they make at that) /forums/images/graemlins/mad.gif /forums/images/graemlins/mad.gif so I decided to change mine (at 8.3 hours)

I bought a filter from the dealer ($18) and some Mobil 1 15-50 oil from Advance Auto. The filter they sold me has 10 milacrons on the side. The one that came on the mower had 40 milacrons on the side of it.
/forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
I'm sure both of these filters were made by some off shore company that Gravely found by price shopping.

My questions:

Which filter is the CORRECT one for this application?

There is no way to get all of the oil out of the system. You can only drain about 1 1/2 quarts at the time. I did this twice and refilled it. I figure this should have diluted the old oil down to about a 1-4 ratio. (3 parts synthetic and 1 part regular) Is this ok?

I am sending these questions to Gravely also but they haven't been the most responsive to emails in the past. They did help me solve a small pto engagement problem I had a while back, but it took quite a while to get an answer and they tend to be very vague with their answers. (Like most manufacturers)

Despite these little bumps in the road, I really like this mower. It gives an excellent cut and is really built well.

Any help you can give me would be much appreciated.

TBone

 

[cphilip]

You should be fine. The base an oil is made from matters very little. Whether its from millons of year old plants or extracted from fresh plants. It's just the tad of old tar left in the refining process of "Dino oil" that is not in the Syntheticaly extracted base that is the only difference. They both lube about the same. The clean synthetic might resist heat breakdown a tad better but overall if your not pushing change intervals its not realy a big deal. It will eventualy right itself. Next change or so. Don't lose any sleep over it.

Sound like the new filter you got is filtering to a smaller particle size. So assuming flow is as good.... which is may or may not be.... it could actualy be a better filter. If it flows as freely as the stock one did.

 

[Mrwurm]

Per my dealer, my Gravely PM260Z has had full synthetic from the start. At 120 hours, I have not changed the filter. I don't remember seeing any schedule to do so. I guess I should check the manual.

I'm thinking that you could have changed out most of the fluid by disconnecting the hoses at the wheel motors. This would be easy to do on mine, but I am not familiar with your model.

 

[TBone]

Thanks Fellas. I am going to try to call Gravely today and ask them which filter is right for it. I cut grass with it Saturday and the 10 milacron filter seemed to be ok. I'm not sure I'd know otherwise unless the flow was severely restricted.

Jerry, my mower is very similar to yours except this is the mini version (34" cut). I haven't looked real close but the wheel motors and hoses are pretty hard to get to on mine. I think my manual says to change the hydraulic oil and filters every 200 hours. I only did it now because I wanted to use the synthetic as they recommended.

I wouldn't have known what they used but I had it in the shop for a minor adjustment and I mentioned that the hydraulic oil was near the add mark and asked them to top it off. The mechanic got a quart of "Pride" 15-40 oil and added enough to bring it up to full. I asked them if that was what was in it and they said it was.

The manufacturers are quick to tell you that you must use everything they specify or your warranty might be voided. Then they let the dealers sell and install anything they want to. Go figure.

TBone

 

[Mrwurm]

Tbone, I've recently noticed that my hydraulic resevour gets really hot after an hour of mowing. I would guess that its at least 200 deg f. I noticed this by accident as I was doing some maintenance right after mowing. The resevour was too hot to touch with a bare hand. Does this seem right ?

 

[TBone]

I don't know Jerry but when I mow my lawn this week-end I'll check mine and let you know if it gets that hot. Mine (and yours too I'm sure) has a cooling fan for the hydraulics so I would guess they generate quite a bit of heat.

My Kubota M4900 gets VERY hot in the rear where the hydraulic/transmission oil circulates. Like you said, so hot I can't hold my hand on it. I'm thinking about changing to synthetic since it is supposed to take the heat better.

TBone