Log splitters

[WinterDeere]

If parts of my splitter system were running hot enough that I could not touch metal parts for more than a few seconds, I would be shutting down to find the problem.

I'm really not sure where you get this from, but it's unnecessarily conservative. The touch test is almost always a poor indicator of safe operating temperature. We humans are relatively fragile, compared to ATF, Viton, and PTFE.

As noted, ATF can run safely all day long at up to 200F. Check the transmission oil temperature on your car, and you will surely find it runs near 190F for 40,000 miles at a time. Hydraulic cylidner seals are typically PTFE (400F) or Viton (450F), they're not going to fail at your assumed maximum of 140F. Even in a poorly-designed seal, where PTFE is not solely under compression, you'd be able to run it to at least 120C (250F)... non-issue.

The only thing that happens at 160F or 180F is that seepage increases slightly, as ATF viscosity drops a bit. Not a serious problem, it's not doing any damage. This is the parallel to the old "oil consumption may increase" warnings posted on oil visocosity tables for vehicle engines, when using lower weight products at higher temperatures.

Of course I'm not arguing with the notion that cooler is better, in general. But I'm also not in any panic when my hydrualic oil tank temperature creeps up above 140°F. It's really not a big deal.

 

[John_Mc]

I'm really not sure where you get this from, but it's unnecessarily conservative. The touch test is almost always a poor indicator of safe operating temperature. We humans are relatively fragile, compared to ATF, Viton, and PTFE.

As noted, ATF can run safely all day long at up to 200F. Check the transmission oil temperature on your car, and you will surely find it runs near 190F for 40,000 miles at a time. Hydraulic cylidner seals are typically PTFE (400F) or Viton (450F), they're not going to fail at your assumed maximum of 140F. Even in a poorly-designed seal, where PTFE is not solely under compression, you'd be able to run it to at least 120C (250F)... non-issue.

The only thing that happens at 160F or 180F is that seepage increases slightly, as ATF viscosity drops a bit. Not a serious problem, it's not doing any damage. This is the parallel to the old "oil consumption may increase" warnings posted on oil visocosity tables for vehicle engines, when using lower weight products at higher temperatures.

Of course I'm not arguing with the notion that cooler is better, in general. But I'm also not in any panic when my hydrualic oil tank temperature creeps up above 140°F. It's really not a big deal.

True IF you are running ATF. Not true for some hydraulic fluids.

The touch test for metals at 140˚ is surprisingly a decent indicator of temperature (actually better than some infrared thermometers when used on bare metals: some don't have an adjustable emissivity, and those with adjustable emissivity but whose owners fail to adjust it properly for the surface being measured are notoriously inaccurate for bare metals.)

Some hydraulic oils start breaking down if they get much above 140. Here's one article on the issue:

The Role of Temperature Control in Hydraulic Oil Reliability

Understand the role of temperature control in hydraulic oil. Learn how viscosity, operating temperature, and high-viscosity index fluids affect system efficiency.

precisionlubrication.com

ATF fluid is generally safe at much higher temperatures 175-225˚F is a typical normal temperature range for automatic transmissions.

 

[WinterDeere]

Good points. But then I wonder who these people are, who'd actually run an old single-weight ISO oil in a log splitter.

Why would anyone do this, when ATF is completely compatible, cheaper, and so much better at both ends of the operating temperature range. Valvoline full-synthetic ATF+4 is only $14/gallon, whereas most ISO type hydraulic oils are more like $22/gallon... for an inferior product, in this application?

 

[John_Mc]

In my case, I use hydraulic fluid because that's what the owner's manual says, and it's what the previous owner had in it when I bought it. When I get around to changing it, I'll probably go with ATF - unless the manufacturer has some reason not to (I have an inquiry in to them). I would appreciate faster warm-up times when using it in the winter.