I work in the oilfields of Colorado. There are oil heaters for the diesel motors that we use every day out here when it is cold. Are there heaters like this for pickups. They run on diesel I believe and circulate the oil in the block while heating it. Is what it looks like to me.

 

Espar and Webasto are the two most common. Cummins makes one as well through one of their sub companies - I did see it on a website, but it was huge and designed for OTR trucks - a bird told me that they have one for pickups too, but I hve yet to confirm it.

 

At work we use alot of Cummins engines in paving equipment. On the 3.9 and 4.5 they have a diesel powered heater. It circulates the coolant to warm the whole engine. You flip the switch and in about 15 min the engine is over 100*. They were introduced to help with cold starting. These machines have numerous hydraulic pumps mounted on them and no way to disengage them.

 

Seems like there was thread on this a while back and a guy posted that you can order a diesel-fired heater for pickups with the CTD from Dodge .... I think he had it from the factory when he ordered his truck.