Every time I read this about a 5.7 HEMI it scratches my eyeballs. Not a single version of the 5.7 HEMI has an oil cooler. Some have an aluminum coolant/oil heat exchanger right above the oil filter. It doesn't do much, but it can help with warming up the oil faster in colder climates.
So, then were does the copper come from in a 5.7 HEMI? It comes from the camshaft bushings, or call them bearings if you will. They have slight imperfections that causes them to shed copper over time. It's harmless.