Well, I had a long conversation with the GMC dealer and they claim they called tech support. They recomended replacing the engine oil cooler. I sent the truck to them and they replaced the oil cooler and flushed the cooling system and replaced all the hoses because of swelling. 2 months later and the oil is back. I appreciate the feed back about the injector cups. When the hoses swell up and start leaking again, I'll get the cups replaced.