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 this symbol on it.
The common hydraulic clutch and brake master cylinder fluid reservoir is filled with either DOT 3 or DOT 4 brake fluid as indicated on the reservoir cap. See Engine Compartment Overview for reservoir location.
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.
Engine Air Cleaner/Filter
Cooling System
Finding a Category (CAT) Station
(XM™ Satellite Radio Service Only)
Removing the Flat Tire and
Installing the Spare Tire