oil in my radiator Reservoir

[Hammerhead]

Yes, mine is a heat exchanger mounted to the top of the tranny. Paccar usses this type primarily, (unless internal cooler) but for some stupid reason KW & Pete have different port outputs???
My tranny oil emulsion coloring was grayish/silver, with red coolant.

I'm not saying this is the OP's problem, just suggesting to do oil analasys to properly eliminate all coolant used components from the equation first. I'd hate to see you spend the time & $$ on an engine oil cooler to next week find out it was your tranny.

Here is a pic of the emulsion scraped out of the surge tank from my issue.