My GSR tranny is having a bit of a problem. When I put my 4th motor in the spring seal that stops oil from leaking out of the half shaft broke.

Long story short I have to keep adding oil to the tranny becuase it leaks a little. Well it got to the point where i was low on oil and it kept poping out of 5th. So i added more oil now, I can push the clutch in and put in 5th but when i release the clutch, it will grind like hell and wont even catch to stay in. I tried rev matching, everything. So i am guessing it could possible be a syncro but syncros help it go in. It goes in fine, but wont catch if that makes sense.

Cliff Notes: 5th gear will go in but wont stay in at all, just grinds and kicks the shifter back into neutral.

 

Time for a rebuild cause your tranny ran out of oil at some point.

 

Syncros help "get into gear" but also keep the transmission "in that gear".
1.Fix the leak, 2. replace 5th gear syncro or, 3. rebuild your transmission