I have a G56 6 speed in my truck that is hard to get into 3rd and 4th when its cold on the up shift and down shifting is almost impossible. Two different dealers told me this is normal . also you can feel the gears bumping going into 3rd on upshift.

 

I can only relate a semi-cold experience I had recently as I live in San Diego. We were in Bryce Canyon and awoke to a 27* morning. Upon takeoff my 2-3 shift was a bit stiff but everything loosened up after a run through town after a few blocks. I replaced my stock fluid w/Amsoil Universal ATF when new which smoothed it out marginally. My knees don't work to well until I've warmed them up also.

 

Mine is a little stiff on upshifts and downshifts when cold too. It has been that way since new. Once warmed, 5th is the only gear that always gives a little feed back, but nothing bad.

 

you need to change the fluid more often in these trannies to keep them running good

 

They'll say its normal but its not IMO.

Mine is a PITA to shift into 3rd when its cold. Like 5 seconds to finally get it to ease into gear. I can jam it in,but it crunches and that can't be good.

Downshifting into 2nd or 3rd unless fully warm isn't gonna happen. Its an even bigger PITA to time the light to be sure you're completely stopped so you can get it into the appropriate gear.

My dads G56 behind his 6.7 is as smooth as can be. Downshift,upshift cold,warm its very easy to drive.

I tried Amsoil and if anything it made it worse. I think the Amsoil might have a little less viscosity and the thinner fluid might not have as much cushioning.

If I had to do it over,I'd have gotten the auto. Fighting with my truck to shift six months out of the year pisses me off.

 

And your suggested fluid of choice and frequency is????????

 

The G56 in my 06 shifts great. I do notice a very slight amount of tension when cold and the 2-3 shift. Usually only once or twice and then it is fine.

I also live in the desert south west so my cold is like 27°-30°F for a week or so. My typical cold morning is the mid to upper 30's

I changed my fluid at 45k miles and just used the Mopar ATF+4 from Wal-Mart. I did the trans and t-case even though they still looked new.

 

Synchros can get glazed and not provide the friction needed to match the gear speeds in the tranny. This may not be your issue but I use high RPM and a downshift with solid pressure on the stick to scuff them a bit in all my manuals when they act up (I have 3 totally different manuals).

It may not work for you, but may be worth a try.

Cya

 

ATF4 and at about every 35k to 45 k if you tow like i do. already had one start to go bad at 10k lasted to about 52k

 

One data point, My G56 shifting does not change with the weather (-15 to 110 F), but it always feels like the clutch is dragging a bit. Trying to shift out of reverse while moving forward is difficult.

 

Mine shifts fine in all temperatures, however 5th will give some feedback if I’m in too much of a hurry. I have to take a bit more time and make sure it goes through the gate. It is geared so low downshifting to 3rd or less doesn’t do much good.

 

mine shifts perfectly from 110~ to 10~. never changes.

 

Mine too. Always smooth as silk with Amsoil ATF4. Can not say the same for the OEM clutch...it slips on Smarty SW #6.

 

Mine shifts fine, no issues. The only time it shifted stiffly was when the temps were about 10*f. I can say that the same stiffness applied to every standard tranny I have owned when the temps were really cold. There have been many of the stiff shifts in 45 or so years of standard trannys and actually less stiffness in the G56 than the others. I changed my tranny fluid to the Amsoil ATF at 10K or so, changed it again at 35K.

CD

 

Mine shifts fine, way better than the NV5600 in the last truck, but I do notice when it is cold if I don't hit about 2300 or higher in 2nd shifting to 3rd can be a touch bumpy.

In warm weather, or once the truck is warm, it shifts like a sports car.