20 Most Recent 2008 Hummer H2 - Page 5 Questions & Answers

I would suggest that there is no water in the cooling system or no oil in the sump and that the motor has either seized or failed from excessive heat.

Replace it because the only place that will service it is the dealer and that it what they are going to do.

Either you have a bad oil pump, or your oil sending unit is bad. You can easily find either at your corner auto parts store. (Autozone, Advanced Autoparts, Napa, Etc.)

Your oil is low or you have a bad oil pressure switch / sensor

Check the condition of the transfer box.

Sounds like a blow or cracked head gasket, the white smoke is either water or coolant being burned in the motor. With this type motor, I would get it checked ASAP before any more damage is done to the motor.