Squealing hydraulic pump

[dfkrug]

Do I need to drain the loader circuit completely too or will the 80w-90 mix
with the THF?

I would try to get as much out of the loader as I could. If you do not have a way to lift the loader
up while the tractor is not running, then you may want to disconnect hoses from each cyl and
push/pull them to get the oil out.

Messy job, I know, but a good idea.