The oil will not affect the motion (at least not until a bearing locks up from lack of lubrication. since most the bearing are ball or needle bearings, it would take a long time.
Did the tractor move properly before you changed the oil, or were you changing the oil to try to fix a bad clutch?. Your clutch pedal should have a minimum of 1" of free travel, 1.5 would be better. Is the clutch fully releasing (pedal coming all the way up with free travel)?
gear oil is for the trans, you can use trans/hydraulic (tractor transmission oil). The manual calls for motor oil, but I think that is because they don't have the variety of oils we have in China. MT-5 is yellow metal friently. the only yellow metal is in thrust washers used in the differential, but might as well keep high sulfer out of there.