Thank You. I actually just changed the filter today. It's had about 20K on it. Never really mattered whether it was warm or cold.
I'll try it out tommorrow. The forum here has helped me figure out fuel filters go at about 8K.
yes fram is a cheapo... some guys will argue it... but find a WIX at least.. (napa and carquest label wix filters) fleetguards are more expensive, but how much is too much for clean fuel? cut one open sometime...
as for the block heater.. here is another GREAT thing from GM. The block heater is a sweet deal because it circulates your coolant and blows a little air out of the defrost even to keep the ice off. the other thing it does is heat the fuel. there are 3 temperature sensors on the fuel system of any duramax and when you use the heater above 30*F outside, the fuel will get too hot and put your truck into safe mode without tripping a code. it will run terrible wide open throttle and until reset by leaving the battery cables off overnight or by a GM tech, the truck will continue to run like crap until it throws a code. BUT it feels like the filter is dirty when the temp sensor is messed up. it took me FOREVER to learn this the "hard way" so now i know... and now you know my brother