Hard Shifting

I have a 1997 Nissan truck, with a 5-speed manual trans. It has 126K miles. Especially when it’s cold outside, I can’t shift from 1st to 2nd, or do so with difficulty. All other gears are OK. I have to shift from 1st to 3rd and then after the truck warms up I can shift to 2nd. I’ve already replaced the gear oil in the transmission and have checked the hydraulic clutch fluid. What’s the problem?

What weight gear oil did you use? A higher number would make for a stiffer shift when cold. I made this mistake once, and went back to factory-spec gear lube of 75w-90. That fixed it.

I used 85W-140, GL-5. Too heavy??

The fact your concern is only with the 1st to 2nd shift leads me to believe your problem is internal transmission related as a lubrication mismatch would show a sympton in all gears.

Does your trans call for “gear oil” or is there a ATF or similar fluid requirement for your trans.

That’s what I put in my '90 Toyota when that happened. Replace with 75W-90, and see if it clears up.

The owner’s manual calls for API GL-4 gear oil in the manual transmission.

Thank you; I think this inexpensive solution is at least worth a shot.