Originally Posted by rikkd

I have one as well. Plus the extra pipes that are leftover from the mod. Don't want them and will ship them if whoever wants them pays shipping.

Originally Posted by Extinct

In my opinion, yes. The radiator is supposed to affect maximum cooling capacity/temperature. The manufacturers size radiators based on a theoretical maximum load at a maximum ambient temperature. The thermostat is supposed to control the minimum engine temperature. However the issue on the D2 is that the factory thermostat design is incredibly unreliable and on top of that it has a bypass system so that there are two modes of failure - complete and partial. Complete is actually easy, truck won't make it around the block without overheating. I have bought probably half a dozen in that condition. Partial is harder to diagnose, the truck runs hotter than it should because the bypass valve does not close all the way and allows some portion of the coolant to bypass the radiator. Owner runs around changing radiator, water pump, thermostat, etc. never quite sure what the problem is. Inline thermostat is more reliable relative to factory design for complete failure and there is no bypass valve so the partial failure is eliminated. I still have two brand new factory thermostats I am willing to send to anyone willing to pay shipping.

Not true, the D2 ECU puts the engine in closed loop fueling mode less than a minute after startup at which point the oxygen sensors control the fuel mixture at an average of 14.7:1. You can see this clearly in this video: https://youtu.be/UNzi30G2_Kk?si=HFK43BGLacG3kQpo

I did not realize 60w was even available, that is probably some of your fuel mileage issue. Anyway most people running the inline report much more consistent temps, typical between 183-190.

That is what the factory throttle body heater is for. At 20 below there is probably some risk of that happening, you might want to keep the throttlebody heater.