Engine Oil Additives/Engine Oil Flushes
Do not add anything to the oil. The recommended oils with the dexos specification and displaying the dexos certification mark are all that is needed for good performance and engine protection.
Engine oil system flushes are not recommended and could cause engine damage not covered by the vehicle warranty.
See also:
Insuring the Vehicle
Protect your investment in the GM vehicle with comprehensive and collision insurance coverage. There are significant differences in the quality of coverage afforded by various insurance policy terms.
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Underbody Maintenance
Use plain water to flush dirt and debris from the vehicle's underbody.
Your dealer or an underbody car washing system can do this. If not removed, rust and corrosion can develop. ...
Fuel E85 (85% Ethanol)
Vehicles that have a FlexFuel badge and a yellow fuel cap can use either unleaded
gasoline or ethanol fuel containing up to 85% ethanol (E85). For all other vehicles,
use only the unleaded gasolin ...