Originally Posted by Jsolo

The upper gears should be easier because the rpm differences between are smaller. I recall reading that the lower gears have multiple syncro's vs the upper which only have one. This sheds light on why the upper gears can be a bit notchy.

The 1-3 is more a function of timing the clutch/rpm differences just right. Even when timed just right, 5-6 is just not as smooth as say 1-2 or 2-3.

The cold temp issue is the trans fluid. As I mentioned MT85 worked great initially then went to crap. The nissan fluid is not as smooth as MT85 but works year round (or so we shall see this winter). Pick your poison