Had a real head scratcher today while changing oil in my B2650. Picked up a jug of Shell Rotella T6 at Wallyworld, as Im switching it over to synthetic from the Kubota 10w-30. I use Mobil1 in all my gas vehicles and the 5 qt jug is usually just about right for my needs. As I was refilling tractor, I noticed that most of the jug of T6 was in, but barely registering on the dipstick...I kept adding, started tractor and let run, then stop and waited. After emptying the jug, I was just below the halfway mark on dipstick..I am getting really confused, because the WSM calls for 4.2 US qts, and I have already added 5. After I came back in house and thought about it for awhile, imagine my surprise when I went out and checked the Shell Rotella jug....only 4 qts!!! DUH!!!