Oil leak

Hopefully it's just a hose clamp on the transmission cooler. Also the tranny fluid runs through the radiator so check those connections too.

This is a little better explanation of the whole system

http://www.prenhall.com/autoweb/sample/thiessen.pdf

Ed Manifold wrote:
Thanks Bret and Dennis and I will check the fittings in fact on my old ford pick-up I had the lines break inside the radiator and my C-6 transmission was ruined. What is the second radiator, is that called the inter-cooler and what does it do and what runs through it. The leak seems to be coming from up higher on the radiators.

Sounds like a loose fitting. This may sound strange but the way I have identified fluid leaks in my 40+ years in the business is to tap the fluid with your finger and then taste it. Yes, taste it on the end of your tongue. If it's Coolant it will have a Sweet taste. Trust me, it won't kill you.
Now, once you have determined it is an oil leak the next step is to find the source. Cleaning the area with a spray can of Brake Clean will help because these leaks can an do migrate from the source during operation due to air movement etc.
Once you know the source you can figure out how to fix it.

The second cooling section is the Inter-Cooler, CAC, After Cooler etc. It's purpose is to cool the air off the Turbocharger that is being pumped into the Engine. Without getting really long winded, attached is a link that will give you the basic idea of how your Turbocharger works and the need for the Intercooler. Good Bedtime Reading.

http://www.tonglint.com/at_Turbocharger%20Working%20principle_6.htm

The other "radiator" is the CAC (Charge Air Cooler), also called After-cooler, also called Inter-cooler.

It is in front of (front of coach) the radiator.

It needs to be cleaned from the FRONT, which is where the dirt collects.

Thanks Bret and Dennis and I will check the fittings in fact on my old ford pick-up I had the lines break inside the radiator and my C-6 transmission was ruined. What is the second radiator, is that called the inter-cooler and what does it do and what runs through it. The leak seems to be coming from up higher on the radiators.

I, too would suspect it's a transmission cooler..there should be two fittings, one on each side of the lower portion of the radiator. If you can get in there, make sure those fitting are tight......Dennis

Check with your chassis maker, but most DP's have a transmission cooler in the radiator. Might clean the connections and recheck for the source of the leak.