I'm using an M7040 now & I change oil @ 150 hours. I think that's a little earlier than the manual calls for but I feel comfortable with it and did the same with the M5030 it replaced. I'll look at the manual next time I'm in the shop and tell you for sure what it suggests. I know the break-in service was at 50hr.
Sold theKubota L2250DT and now have a Kubota M4900DT
Blksim.
My M4900 manual also covers the M6800. Every 200 hrs for engine filter and oil. With the hydraulic oil filter at 300 hrs and hydraulic/trans fluid at 600 hrs.
Hope this helps.
BTW these are great tractors!
Dave