I used to use jacks, at work. The tractor fluid works fine. I'd think that
transmission fluid is OK, also. I found to fill the reservoir when the jack
is "all the way down" helps keep from over filling the tank. Full, minus a
bit for air space is what worked for me.
You cound always add "a bit" and then a bit more. See what allows you to
raise the jack all the way up.
Christopher A. Young
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I have a 20ton bottle jack that is low on fluid. I found the fill plug
on the side of the cylinder and put in some fluid. I did not have much
fluid on hand, so I put in what I had. It now jacks up halfway, so I
know it works, but needs more fluid. The question is how full should I
make it? Do I fill it until it runs out the fill plug, or another
Also, I was wondering if I can use general purpose hydraulic tractor
fluid rather than the more costly small bottles labelled as "hydraulic
I found several websites abotu this. None said how much fluid to add.
More than one said DO NOT use brake fluid. All seemed to recommend the
actual "hydraulic jack fluid", one said transmission fluid works, but is
not recommended. Yet none suggested hydraulic tractor fluid (which
operates all hydraulic cylinders that are connected to the tractor, and
thus is used in the same way). It's a lot cheaper per ounce to buy a
gallon of tractor fluid instead of a quart or pint of jack fluid.