You have to take the door apart
1991 Corsica its under the trottle body
For a 1991 Chevrolet Corsica : My Chilton's Auto Repair Manual shows : ( 15.6 U.S. gallons )
Remove the wiring harness from the back of your 1991 Chevy Corsica turn signal. Remove the turn signal retaining bolts. The entire turn signal will come out. Reverse the process to install the new turn signal.
It doesn't have one, it is distributorless.
13.6 gallons
Green coolant (prestone, etc)
Depends on which engine it has. Try a Google Search.
16.5 to 17.1 gal
As soon as you pop the hood, it should be to the left of the engine. it is visible from top view.
Pull it out and put a new one in. Located: FRONT SEATING AREA, DRIVER SIDE, UNDER DASH, MOUNTED ON DRIVER SIDE OF STEERING COLUMN
if its a manual transmission its attached to the clutch pedal housing if its an automatic its the shifter
its behind the coil packs on the back of block