Coolant in Oil

[pecka]

Well over the weekend I noticed my car has started to mix coolant into the oil. I have done some research and from what I have come up with it could be the headgasket, oil cooler, or turbo. Which one is the most common problem when it comes to a DSM? My car is a 95 and has roughly 100,000 miles on it. Is there any way to test the oil cooler to see if that is in fact the problem? I will be doing a compression test in the next few days, but if it were in fact a headgasket wouldn't the mixing go both ways? I checked the coolant and there seems to be no sign of oil in it. Any other suggestions would be greatly appreciated! Thanks