oil in coolant reservoir but not milky
I am going to be picking up an 01 F250 with the 7.3 in it with 172k miles. When I first started it up it sucked in almost all of the coolant from the reservoir quick but wasnt smoking or idling funny. Then when I shut it down after about 5 min the res filled back up to the correct line so I opened it up and noticed the coolant was dark brown but not milky like you would normally think with water and oil mixing. It still flowed like regular coolant. Not really sure where to start but I have read about the oil cooler, injector cups.
Any advise of where to look or start would be greatly appreciated