Hoping bad oil cooler? Help!

[WillMo]

I've got a 2006 Cayenne S and just had an issue the other day where it The temperature started to climb fast and when I checked the coolant reservoir I had oil in the water.  There is no oil in the crankcase but it was down 3 quarts. I'm due for an oil change so I expected it a little over 3 quarts was a lot. It has 125,000 miles on it. It is still running perfectly, was not blowing any smoke or doing anything to indicate anything internal in the engine like a head gasket or a cracked head or block.  I've had a very slow water leak for the last two years.  I would have to add 1 to 2 quarts of water every 3 to 4 weeks. As soon as it indicated to check the coolant I always topped it off and it would only take 2 quarts. As any freeze was getting expensive I just kept filling it with water waiting for the day when I had enough cash on hand to find the problem and fix it. It always had run perfectly at 180° prior to to this incident. In my younger days I was an ASE certified mechanic but at 56 I really don't feel like digging into this job anymore than I have to, especially if it's a losing cause. I'm posting this in hopes that someone can tell me if the oil cooler is water cooled or air cooled.  I have not had  any oil leaks. I'm hoping that because there was no antifreeze that may be in the two years of using the straight water the cooler rotted through. Any advice I can get here would help greatly as finances are a ***** these days after a tough divorce and I still owe six grand on the car so this is a bit of a nightmare. 

[bigbuzuki]

The oil cooler indeed is water cooled.

I had my oil heat exchanger changed on my 2003 Cayenne turbo last December as it was cracked with oil found in the coolant system.

Change it asap.

Part number for the S and turbo is the same being 948 107 276 03.