On my B2650's first service interval (50 hrs. filter change only) I decided to first drop the oil into a brand new clean 5 gallon pail. Thinking it would avoid a mess due to any unknowns, my screw ups, etc. rather than counting on a very quick filter change without dropping the oil. It would give me all the time in the world for the first change to see how things came apart and fit going back together and I would just pour it back in afterwards. Plus, I could look for any metal shavings, etc. in the bottom of the pail.
After draining the oil I decided not to reuse it. It was discolored, had a little scum in it, along with maybe some fine machining odds and ends. It just didn't seem right to put it back in so off to the dealer for a new bucket of SUDT2. The next scheduled fluid change resulted in nice clean hydraulic oil removed from the transmission.
If this is your first 50 hour service.....a clean bucket is cheap insurance against any little mishaps that might lead to a mess of hydraulic fluid on your floor.