I have a 2003 Chevy Silverado 1500 ext. Cab 4x4. The Oil Temp. Gauge is going from the middle to extremely hot and drops, well below the hot mark. My Odometer and Rpm's will drop when this happens. But it seems to be running fine. Any advice or suggestions as to why or how I go about getting it checked without taking it in to the Dealership? I just purchased it off a lot in October and the Dealer mentioned an O2 Sensor that needed to be cleaned. Also informed me of a little mouse that started to make a home inside but assured me it was dealt with properly as well as fixing the said problem....a little frustrated
However I did have it serviced immediately after buying it. $400. In belts and flushing the system including an oil change. And it still seems to happen....??

 

Your odometer should not drop at all ever unless your thinking of something different the odometer tells you how many miles are on the truck if its dropping at all id bet on the instrument cluster being the problem

 

I agree its going to be the cluster as they had recalls on them. I have a 2004 Crew Cab 1500 and mine did the same. I went on Ebay and purchased an SS one and had them upload the DIC for me. They charged me 200. They program it to your trucks VIN, I went with the SS mostly because of the Trans temp gauge.