So I bought an i35 recently.I test drove it when the car had been driven home from the guys work so it was nice and warmed up. So I didnt notice the transmission issue since it only happens when it is cold.

When cold, the shift from 1 to 2 is hard. From 2 to 3 it seems to rev and slip into 3rd. 3rd to 4th is fine.

When warmed up, it seems to shift fine. I have drained and re-added fluid 4 time (16 quarts) to dilute and flush the old fluid out. Fluid was pretty black. I would drain, measure, and refill. Go drive 5 miles. Come back and repeat. I filtered all the old fluid and didnt see any metal in the filter. So that is good. I bought 8 more quarts today to drain twice more. By that point, the fluid should be thoroughly changed out. I am using Castrol Import Multi Vehicle transmission fluid.

I just bought a new seal and filter, 8 more quarts of of oil, and will be dropping the pan. I couldnt find the self sealing screws locally, so I will be using some blue permatex thread sealer.

Any ideas what might be causing this behavior?

 

I am having the same issue with my 2004 I35. It shifts rough from 1st to 2nd when cold. Have you been able figure out what is going on?

 

Try adding some Lubegard Red.

 

FWIT, the LubeGard company recommends that you use the LubeGard Platinum product in the Nissan/Infiniti transmission instead of the red. A 10 oz bottle is the recommended amount.

 

Has anyone tried the LubeGuard flush?

http://lubegard.com/SearchByCategory...smission+Flush#

 

My old thread resurrected! Transmission is shifting better. I change the tranny fluid every over oil change. I might try some of this LubeGard Platinum.

 

I recommend Lucas oil Trans Fix; use it annually with full trans fluid flush in my '97 i30 and '03 maxima!

 

That sounds excessive.