I changed my trans fluid last month at 40,000 miles and now when I go to shift from 2nd to 3rd it grinds. I thought I put the wrong fluid in (I used some left over from the Mack), so I drained it and put in Castrol Syntec 75/90 back in. It didn't change a thing. The oil that came out wasn't the cleanest in the world and it was only in for about 2000 miles or less.

I had the truck at the dealer and the service rep. said I might have a syncro going out. He's had a couple in with that problem in the last year. I guess I'll have to watch it and when it gets real bad, take it in and leave it over night. (It only does it on the first couple of shifts until the truck warms up.)

At least it's still covered under the 7 year/70,000 mile power train warranty. (Which I didn't know I had. I knew about the 100,000 on the motor.)

Has anyone had a problem like this?

 

I've had it where I would go to shift to 3rd, and its like hitting a solid wall, and won't go it. No grinding, just wont go in.

Its not a everyday thing, but still anoying.

 

Mine doesn't really grind, but "bumps" a couple times when I hit 3rd. I find it slips in better if I rev to about 2500 in 2nd before shifting.

I've changed to Redline MTL, and thought it improved for a bit. I'm sure mine isn't bad enough yet that Dodge would consider doing the tranny as a warranty issue unless it gets worse, but before it hits 7/70 I think I'll try.

 

I read your post several times.You state that you put 75w90 in the trans??? Thats a very WRONG fliud.I can see why it would grind or be hard to shift.Amsoil/Redline/Mopar make a correct fliud for the NV5600.It takes like a 5 or 10w30 weight fliud.Some use to use Amsoil 10w30 before they came out with a correct gear oil for the NV5600.But the point is its NOT a 80w90 or what not weight that goes in that unit.Besides being way to thick some gear oils are not set up for the type brass and metals used in certain manual transmissions.