For vehicles with a manual transmission, it is not necessary to regularly check brake/clutch fluid unless there is a leak suspected.
Adding fluid will not correct a leak.
A fluid loss in this system could indicate a problem. Have the system inspected and repaired.
When to Check and What to Use

The brake/hydraulic clutch fluid reservoir cap has either a symbol or text specifying the type of brake fluid. The common brake/clutch fluid reservoir is filled with GM approved DOT 3 brake fluid as indicated on the reservoir cap.
How to Check and Add Fluid
Visually check the brake/clutch fluid reservoir to make sure the fluid level is at the MIN (minimum) line on the side of the reservoir. The brake/ hydraulic clutch fluid system should be closed and sealed.
Do not remove the cap to check the fluid level or to top off the fluid level.
Remove the cap only when necessary to add the proper fluid until the level reaches the MIN line.
Manual Transmission Fluid
Engine Air Cleaner/FilterInstallation Procedure
Remove all mounds or loose pieces of urethane adhesive from the
pinch-weld area.
Inspect for any of the following problems in order to help prevent
future breakage of the window:
High weld
Solder spots
Hardened sealer
Any other obstruction or irregularity in the pinch-weld fla ...
Driver or Passenger Seat Retractor Side Belt Replacement
Warning: Refer to SIR Warning in the Preface section.
Warning: In order to prevent accidental deployment and the risk of personal
injury, do not dispose of an undeployed inflatable
restraint seat belt pretensioner as normal shop waste. Undeployed seat belt
pretensioners contain substance ...
Visual Aiming Preparation Procedure
Important: Some state and local laws specify requirements for
headlamp aim. Comply with all of these laws when performing any
headlamp aiming operations.
Headlamp aim should be checked:
When a new headlamp capsule is installed.
If service or repairs to the front end area have, or may have, ...