Sorry, the NHTSA has not posted this TSB document yet.
You can still get the detailed info from Chevrolet for this TSB. Call your local Chevrolet dealer's service department & ask for a copy of TSB# 12-06-04-002E.
Affected Component: ENGINE AND ENGINE COOLING:EXHAUST SYSTEM:EMISSION CONTROL
Information on Exhaust Fluid Range, Exhaust Fluid Quality Poor, Service Exhaust Fluid System or Service
Emission System Driver Information Center Messages