Well this tractor came with the farm.
It was under 30 inches of dust and lead paint chips.
There was aluminum foil over the top of the filler tube on the hydraulic tank. I think the missing cap also had a dipstick.
Big old foot long crack on the left side of the engine block.
One day I dragged it out & aired up the tires and towed it 1/4 mile up the street to the metal fab shop and had him weld up that crack.
It sat outside his shop through an entire spring rain season and wind blew that foil cap off.
So when it was welded up we towed it home and I got it running.
Hydraulics didn't work at all so I changed the fluid.
The only drain on that system is to remove the rubber hose from the pump. But it's the lowest point on the system.
The oil came out tan colored like coffee with lots of creamer.
So I filled it up, ran the bucket up and down a few times, drained it, and it was just as bad.
Two more times at 50 bucks each (5 gallons of universal hydraulic oil ain't cheap) and it was still coming out tan colored but it was working OK so I said **** it.
I changed it again in 2014, same thing.
In cold temps, what happens is oil can't get to the pump.
I made a new filler tube and cap, using a Milton male coupler on the end of the vent so I can blow air into it using a female coupler and a two foot hose.
Just pressurizing it with my mouth used to get it working but eventually it got so I would have to put 20-30 psi into it before it would work.
The only way to heat the oil is to install a radiator hose type engine heater and hope the oil can disperse heat fast enough not to burn the oil. That's why dipstick heaters aren't good.
The reservoir is pot metal or aluminum. All I know is it's painted, looks like crap and magnets won't stick to it.
I'm just gonna take the top off the reservoir and see what it looks like in there, clean it out, and remove the long steel tube and pull a kerosene soaked rag through it with a wire.
If the tube is that bad I'll figure out a way to cap one end of it and leave it full of kerosene overnight.
I'm not worried about the high pressure side of the system.