The HMMWV uses a common cooler frame containing cores for both transmission fluid and engine oil. 2930-01-168-7911 [2930011687911
Quite often, the cooling fins are damaged (by being bent or collapsed) at the top and bottom of the unit, and often within the main area of the cores themselves.
Our unit had crushed and bent fins on the top, bottom, front and back. The picture above shows use of a fin comb to straighten out the fins. Although we used a Robinair with multiple combs, you could simply acquire a 10 fins/inch comb to accomplish the same task.
Although a tedious and time consuming task, this will ensure not only optimum airflow and cooling, but it also eliminates the somewhat unsightly bent fin situation.