my dd manual tranny is hard shifting when the fluid is cold only in first and second gear. heard it might be a syncro but also heard to mix a 4 to 1 ratio of gear oil and aft (1 gallon gear oil to 1 quart atf) the atf acts as a detergent and helps clean out the trannie. anybody done this or hear if this is a wise idea.

It won't hurt. I use a qt. of atf in the engine of my DD on occasion to keep it clean. You might want to check the clutch adjustment, if it's dragging on the flywheel it will shift hard.