For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition
65 WarningBrake Fluid
The brake master cylinder reservoir is filled with DOT 3 brake fluid as indicatedon the reservoir cap. SeeEngine Compartment Overviewfor the location of the reservoir.There are only two reasons why the brake fluid level in the reservoir might go down:The brake fluid level goes down because of normal ...