Recently I have heard that 5 speeds for firebirds take anything from 30 weight and 90 weight gear oil to automatic tranny fluid. One source said non-world class 5 speeds take the oil and world class takes the tranny fluid. Where would I check on my transmission for a code or number to tell what year it is and if it is a world class or not? My father put that dexIII or whatever tranny fluid in it and it was fine till about 2 weeks ago, now it grinds pretty bad in reverse and shifts hard compared to before.

 

On a 4th gen, Dexron ATF is what is supposed to be in it. Maybe if you gave info on what car this is...

 

Your complaints are most likely the clutch not having enough release clearance (clutch not completely disengaged). This will cause the reverse to grind, and the others gears hard to engage.

 

It's an 84 firebird with the T-5.

 

Got my fluid problem fixed. How would I go about fixing the problem of my clutch not having enough release clearance?