Hot Car = Shifting woes - need help

[Buellrunner]

Car - 1990 C2
Symptoms - When the car is cold, shifts smooth like butter. No issues at all. Once she gets hot (30 mins of driving, city or highway) she doesn't want to shift into 1st at a stop. Hotter it gets, worse the symptoms. If I pump the clutch a couple of times before attempting to put it in first, it helps. Its as if the clutch doesn't fully disengage when I press the pedal in. The clutch does not slip at all when accelerating.

Ive replaced the slave cyl last season, and bled the system. It really helped. The car sat a lot over the canadian winter, and now Im experiencing these symptoms.

My mechanic is recommending a new clutch. I wanted to check with you all about whether this sounds like a clutch issue, or a hydraulic issue. I was thinking that it might be air in the lines, but I dont understand how air might have developed. Also, why would it only show up when the engine is hot?

anyone else experiencing, or have experienced these symptoms? Any thoughts on what this could be?

I believe the hydraulic lines are original, and so is the master cyl. Tranny fluid was changed last season too.

Any help would be much appreciated, as I would rather not spend the $$ if I dont have too.

Thanks!

[Don Plumley]

What kind of tranny gear oil are you using?

[Buellrunner]

Regular non-synthetic recommended oil. Would it make that much of a difference?

[Don Plumley]

It could. Try Mobilube SHC 75W90 LS (this is not the stuff at your corner auto store), or Redline.