Have a 67 loader backhoe with zero history. Yes the cylinders weeped a bit. I topped up the hydraulic fluid with, I don't know, 5-10 gallons? I lost count. It took a lot of oil to bring it up to the sight hole. Anyways, it seems like cylinder leaks are becoming worse now that it has been topped up. Does it make sense that there's more pressure in the system now that it's full of oil?
No it doesn't. You used the cylinders that had been dormant. Maybe it leaked bad before you bought it. Oil is available in many varieties. Old cylinders leak. A machine filled with HyTran is going to leak a bit less than with generic hydraulic oil from Tractor Supply. I use an additive I'll have to look at the jug to say what it is. In the end, You need to repack the cylinders. Not as big a deal as you imagine. You need the correct gland wrench, mine cost $80 something from Amazon. You also need a 1" heavy duty breaker bar & correct socket for the piston nut, assorted blocking, a bed sheet. I like Broken Tractor for packing kits, but Case sometimes matches their price.
Sort of makes sense to me if the seals are old and brittle. Now that you are moving things the seals are most likely failing because they are no longer soft and pliable.
I used it last year and it didn't leak as much as it does this year after I filled the hydraulic fluid. It just seemed coincidental.
So lets think about what you just said. I used it LAST YEAR..... Doesn't sound coincidental to me.
Call or email Dale Wiess for a decent price on about anything needed for a Case machine. http://www.e-backhoeparts.com/