L2501 Kubota compact tractor 25HP. Can't see the line on the sight glass...so I added some UDT... I added a half gallon at a time and then re-checked to look for the line...until it overflowed. At no point could I see the line on the sight glass! Now it is filled to just below the filler opening...so if I use my pinky as a dip stick there is about 3'4' of oil. If I drain some out I propbably still won't be able to see the line and so....is there a better way to determine how much UDT to add?