Diagnostics
OnStar Vehicle Diagnostics will perform a vehicle check every month. It will check the engine, transmission, antilock brakes, and major vehicle systems. It also checks the tire pressures, if the vehicle is equipped with the Tire Pressure Monitoring System.
If a diagnostics check is needed between e-mails, push 
, and an Advisor can run a check.
See also:
Washer Fluid
What to Use
When adding windshield washer fluid, be sure to read the manufacturer's instructions before use. If the vehicle will be operating in an area where the temperature may fall below freezing, ...
Brake System Warning Light
The vehicle brake system consists of two hydraulic circuits. If one circuit is
not working, the remaining circuit can still work to stop the vehicle. For normal
braking performance, both circuits ...
Footnotes — Maintenance Schedule Additional Required Services — Normal
a) Or every two years, whichever comes first. More frequent replacement may be needed if the vehicle is driven in areas with heavy traffic, areas with poor air quality, or areas with high dust levels. ...