You should lubricate the new
Fuel Injector O-ring seals with mineral oil GM P/N 9981704, next install the new fuel injector O-ring seals onto the fuel injector, install a new retainer clip to the fuel injector, then push the fuel injector into the rail socket with the electrical connector end facing outward, and connect the fuel injector harness electrical connector to the fuel injector, finally install the fuel rail assembly.