I bought an inexpensive battery operated transfer pump from Harbor Freight to (possibly) pump out most hydro fluid from the top, swap filter with minimal loss, use same pump to put it back in and top off as needed.
Amazing deals on this Transfer Pump Battery Operated at Harbor Freight. Quality tools & low prices.
www.harborfreight.com
Amazon has similar pumps with automatic shutoff. There's a float at the end of the output hose. Be sure it runs on 2 D cells or more, because power is marginal for higher viscosity fluids.
I used this to pump used UTF out of a big plastic storage bin into 5 gallon buckets for recycle. Very slow, but it worked. I finally put the bin on a little platform to pump downhill, this helped. Overall, far easier than trying to tip that storage bin into a funnel. Slow but no mess!
I use this to refuel the tractors from the 5 gallon jugs (and old UTF buckets with lid intact) that I use for fuel transport. I can also pump fuel out of one tractor for use in another if I don't want to go buy fuel. The automatic shutoff is very handy, recommended.
I then bought a cheap one to transfer drinking water from 6 gallon camp jugs into gallon bottles. This runs on AA batteries. Not recommended, it's slow pumping water. And it wasn't until page three of the manual that I found 'Do Not Use For Drinking Water'. That's not in the Amazon description or labelled on the box.
As for the 12 volt 290 gallon/hour pump - that could get real exciting at 5 gallons per minute. Maybe rig it where you can step on the cable and pull a plug out of a socket to disconnect the power quickly.
Those have a warning against volatile fuel. UTF and hydraulic fluid might be ok, I don't know.
Here's an application of that 12 volt pump for watering. Output is comparable to a garden hose.
(But a year later to deliver more water per trip to 100+ new orchard trees, I replaced this with a sump pump in an IBC tote).