Cummins oil cooler - brazed or soldered? - what materials??

Schafflund, Germany
Thread starter
Does anybody know how a Cummins 3.9 or 5.9 OEM oil cooler is being held together and what materials are involved? Are the plates and oil passages made of copper or brass, and are they brazed or merely just soldered together with something like 70/30 solder? I would like to know as I am reconsidering my choice of coolant and cannot seem to accept that an oil to water heat exchanger like that could get away being made like any "weepy" automotive copper radiator.