I just got my oil changed in my 2002 4.2 4x4 Chevy Trailblazer. 3 days later - my oil pressure low indicator start flashing and the gauge would drop to zero then the display would flash stop engine. I immediately pulled over and turned the truck off. Checked my oil level. Then I realized I needed to wait until it cooled. Once it cooled the oil level still showed that it was fine on the stick. I started the truck back up and began to back out. In reverse the car seemed to stop on its own without me applying the brake after a few feet. I put it back in drive and it seemed to drag. I called and then took it back to the folks that did my oil change. One of the service people took the car to check it out. He came back and said, your 4x4 was on. I contested since I am the only one who drives and I don't use the 4x4 at all. But I drove it and none of the issues occurred.....until yesterday. This time, I no that the 4x4 isn't on and I am having the same issues. Is there anyone who knows what might be going on. I know that there is a chance that I may have to get the oil pump replace (God no!) but I am really hoping that it is something less complex and inexpensive than that. Could there have been something that the service people didn't put on right that may be causing the malfunction. I want to go in and have some ideas if that is a possibility. Sorry for the long thread. Wanted to make sure I gave all of the information for a clear answer. Thanks Trailvoy!