[obermd]

At 100K miles it could also be a sign that the clutch pad needs to be replaced. Also, do you have a odometer picture?

 

[obermd]

The odometer picture is to award a 100,000 mile badge.

 

[obermd]

Why do you expect changing transmission oil to reflect the way clutch works ? It may improve shifting but not clutch "feel". Earlier Cruzes (2010-2012) are known to have an agressive clutch return feeling (or whatever is the right word for it). After some miles you will develope skills... and muscles in your foot as well

The OEM synchromesh is too thin. The AMSOil synchromesh is a thicker fluid and generally makes the gear box work smoother. It does change how the clutch feels but it doesn't do anything for a worn out clutch.

 

[obermd]

I'm not trying to improve the clutch with the fluid, that's silly. I'm trying to improve the shifting. The clutch works as intended, it's just heavy. Nothing to be done with that..although I may get it replaced sometime in the future or if it turns into a bigger issue.
The gears are another story. I drained it and as I suspected it, it was never changed and it was dark brownish, almost black. Remind you, this car was bought with 95,000 miles.
I put a new, but generic gear fluid in it, but shifting through gears is still too rough, although the new fluid did improve, not to mention, the fluid that was in there, wasn't even enough (about 1.5 quart came out).

The dark color may be anti-corrosion agents the GM puts in the transmission during manufacture. I'm hoping you put 2.25-2.4 qts back in.