Accert water oil exchange program?

A buddy of mines 2006 Accert started getting a little oil color in the water about a year ago, now it's started showing antifreeze in the oil analysis, and color is starting to turn into oil scum in water reservoir.

First he disconnected the transmission cooler

Then he replaced the engine oil cooler

He just got the analysis results back and it is still getting antifreeze in the oil it's not enough to scum up the filler cap or the dip stick yet.
Where should he look next? Pull the pan and pressurize water to see if a sleeve is leaking?
any pointers would be great
The motor has about 570,000 miles on.
And turning the the freshly cleaned radiator scummy

 

Thanks kw9s
I was hoping I missed the obvious
or that reman oil coolers can be bad or such like because of the oil and water going both ways