Oil Cooler

[LMRanger]

I have a 2015 R25SC with the D3-150 engine. My question is, does the oil cooler use raw water to cool the oil or circulating engine coolant?
Trying to plan long term maintenance and looking at servicing the after cooler and engine cooler.
The boat is operated in sea water and not kept on a trailer.

Ralph

 

[BB marine]

The oil cooler is part of the freshwater cooling system. It is a plate cooler. Draining and flushing the engine antifreeze every other year for the preventative maintenance of the D3.