My skid-steer owner's manual calls for ISO VG 46. -30C is common up here. What winter hydraulic oil do you guys recommend?
I have a Bobcat A300. It is my third Bobcat. I use Bobcat's own hydraulic oil and have had no problems. It is important to warm the hydraulics up before giving the machine a load to handle. Other machines we have use synthetic hydraulic oil, and our John Deere crawlers use 0-40 year around. We try to not use the big machines in temperatures below -30C unless we can keep them going around the clock.
I'd say a ISO(AW)46 or 32 would work fine for colder temps. ISO 46(20w) ISO 32(thick 10w)
At a minimum let it warm up at least 10-15minutes. You would be surprised how long it takes to warm up all the oil in the reservoir. ISO 32 should work fine as long as you keep the oil below ~175F in the summer, otherwise you could smoke your pump. The thinner oil will help minimize wear cause during startup. ISZ
How do you warm up the hydraulic oil? Simply let the machine idle?
Yes let it idle at first then gently increase the rpms
You start out letting it idle until the engine starts getting warm. Then, if possible, work it gently till the hydraulics start to heat up. If that isn't possible then you can hold the hydraulics over relief, something like 15 seconds at relief, 5-10 seconds off. ISZ
Um, stupid question from a newbie here... What does that mean?
In cold temps, what you want to do is let the unit idle for a few mins, then increase RPM's a little once the engine is a little warmer. Then work the Hydraulics over relief intermittantly. "Relief" is when the hydraulic pressure relief valve is open and oil is going through the relief valve. This is done easily by working a hydraulic function to the end of its limit and then continue to hold that function open. IE: curl your bucket back until it is completely curled and then continue to try to curl it further. Cheers
In our area (northern Alberta) most construction equipment either have block heaters that cana be plugged in to electricity, or a diesel fired heater which warms the engine up before the operator arrives. The majority also circulate the warmed coolant through the hydraulic tank also. Many hiway trucks that use hydraulics for winches, pumps, pickers etc. have an exhaust pipe pass through their hydraulic tank so the hydraulic oil is warm when they arrive at the worksite. If warming the oil is not possible, the should be operated with no load (raise and lower an empty bucket etc.) the cold oil needs to be circulated out of the exposed lines without a load to allow the oil to flow without excessive pressures.
Gotta be careful when running a machine with cold oil. A lot of the components aren't designed to continuously operate with cold, viscous oil. At those temps, is almost like pumping honey through your system and you can see much higher pressures (start popping filters, etc). You're usually circulating oil through the system, so best to let the machine idle and then slowly start cycling the implement functions to let the oil get nice and warm. Stalling the bucket is a good way to speed up the process, but don't do this unless you've let the machine run a bit.