3rd gear grinding only when warm

[MrGriff750]

Well heres the deal....when my car is "cold" (in the first 10-15 min of operating it) I dont have any problems shifting and everything is smooth. However, after a while of driving, 3rd gear begins to lightly grind then progresses to a heavy grind which remains until i let the car sit overnight. I changed my gear oil to GM synchromesh and that basically made everything smoother but didnt affect the grind entering third. Im goin to try to adjust the clutch rod connected to the pedal in the morning and see if that makes a difference because my engagement point seems low.
Anybody have any suggestions? Could it possibly be the clutch itself?
Thanks all.

 

[Ultimatedsm]

If it was the clutch, it would be every gear. I think the syncro is just going bad in general. Try putting some Syncro shift II in there and let us know whats happening.

 

[perley03]

You are running too thin of an oil in the tranny. When it heats up it thins out and therefore not providing enough lubrication for the synchro. Try mixing your oil, synchromesh and some synthetic 75-90 gear oil. I had the same problem, except 2nd not 3rd, and changed the oil to BG Synchromesh. It was worse, so i took it to a friend that works at a tranny shop and talked to the owner/mechanic and he said im using too thin of a oil, and he recommended that i mix the oil with something thicker. I just mixed it 50/50 and it shifts great, no grinding and shifts into each gear smoothly.

 

[pnishr]

I was having grinding in 2nd and 3rd. I completely drained the tranny, and went with Royal Purple 75W90, everything's fine now.

 

[TC Mueller]

question about the fluids. do you mix 50 50 in the t-case as well?

 

[perley03]

I have a fwd, so i dont know about the transfer. However, i know 2 people that have awd and they run just straight 75-90w gear oil in the transfer only, because i've helped them top them off a few times before long trips, but i don't know what they run in the tranny.