Yup, we can argue this until that cows come home and still not arrive at an agreement. I'll stick with putting the aux cooler first, on a t-stat, because if I'm working the converter hard it means that I'm also working the engine hard and I don't want to be adding any more heat to it's coolant than necessary. This is particularly important to me when the engine's cooling system is marginal to start with.
Others don't see it that way and that is fine. As long as I don't have to drive their trucks in those conditions I don't care how they decide to do it.
I do recognize that the wetted surface of a liquid to liquid heat exchanger is more effective, per unit of surface area, than a liquid to air heat exchanger. However, I also recognize that the most heat transfer occurs where the temperature difference is the greatest.
