96 4cyl. shifts hard when hot?

I posted this same question already on the gen 1 forum but want to hear from guys building mechanical stuff. My truck shifts stiff (like the linkage is bound on an older car) after about 45 mins of city driving. The engine is at norm temp. I and others think it is the syncros. I bought it with 165k miles, changed fluid with basic cheap stuff. It now has 180k on it. I don't want to drop gear box if I don't have to, to get a few more miles out of it but I need it to run for a little more time. Thinking of running full synthetic. Will it help? Anyone have a favorite brand? I hope it may help to last a little longer. Thanks for the help.

 

My shifting wasn't so much "hard" as it was "notchy" (98 5-speed V6)

I just changed my tranny fluid to full synthetic... feels no different. Probably the synchros.

When I asked my friend who owns/runs a shop he said don't worry about it. It's just more personality for the truck.

 

Thanks, I was afraid of that.

 

same here!