2002 Chevy Tahoe Engin Noise

Hello, in the morning when I first start up my tahoe Z71 my engine seams to make alot of noise, sounds like the rods are nocking sounds like its out of oil, after about 30 to 40 seconds the noises goes away I check the oil. Its ok, I had The oil changes and use suv oil, but it stills does it, I have ask others with the same car and they tell me they don't have that proplem, is there anything I need to know or do. Thanks Richard in the bay area