I was just checking out the service manual for the
L3650 HSTC.
In all the documentation I didn't find anywhere, comments related to overfilling and any issues that might cause.
From following the Hydraulic schematics, there is nothing there to show that a higher level could, or would cause any issues unless they might have left out any foaming or air entrapment due to areas where there may be return oil flowing back into the reservoir under pressure and mixing at a higher level in the return area. This is just my thought based on the schematics and the documentation I have reviewed.
As a reservoir, the holding area seems big enough to support additional fluid. The last time I picked up my unit from the dealership it was filled up over the top of the upper dipstick mark about the same amount as the space between the marks. Given the level surface area inside the rear end assembly where the oil is stored, that could be a gallon or more of extra fluid there, maybe 2 gal (at my current Dealers installed level).
I agree though, once you get to a certain point lots of other things come into play... there could be head pressure that might impact some control valves that may be normally looking at atmospheric (or the internal air pressure of the housing - if that is different) pressure as a normal - but that atmospheric could be increased by the weight of an additional 2 to 5 gallons of fluid.
There is no question that we aren't privy to all the design considerations that make up the operating characteristics of a complex hydrostatic design like this, so we probably need to be within a prescribed level relating to the manufacturers specs. Yes, every time I connect or disconnect an implement (depending on the connectors), there is a loss of oil, that's just the nature of the beast. However, I would venture to guess that without major leaks, you could get quite a few connects and disconnects on various types of hydraulic implements or equipment before an appreciable loss in fluid would negatively impact the functioning of a tractor that has a reasonably maintained hydraulic system. Not to mention that a daily or weekly check would also point out those issues hopefully before it causes operational issues.
Oh, and, by the way , I'm still waiting for rbargeron's guaranteed refund!! (Not that he made any disclaimers that weren't true), he he he ... last I heard was "it's in the mail", but that was over a year ago. I'm thinking with COVID, the mail is just delayed a bit or maybe the mailman thought it was a Ballot from the last presidential Election and tossed it in a field somewhere. It should have sprouted by now!!!!
