I changed my oil yesterday in my 2005 Dodge Ram. When I removed the oil fill cap there was yellow gunk under the cap. A sure sign that antifreeze was leaking into my oil. The oil I drained had no signs of water or antifreeze and the dip stick showed no signs either. It was just under the cap. The only other time this happened to me was on an old Ford van and it turned out to be a head gasket. But that showed signs everywhere not just under the cap. Could it be something simple? The only mechanic that I trust is booked up until next week and I don’t want to damage the truck by driving it. Dose anyone have any ideas or has this happened to you?  

I just discovered the same issue with my 2002 Dodge Dakota 4.7L V8 Engine. This same yellow waxy gunk was also under my oil cap right at the entrance to my PCV valve. I thought maybe the valve was clogged so I cleaned it out. However, I still have a performance problem with my truck. It idles fine, however it seems like the truck is starving for fuel or running very lean when giving it gas. Someone told me its probably a bad gasket on the intake manifold or the manifold itself is warped (mine is made of a plastic composite) and some of the antifreeze is being pulled into one or more of the cylinders. I don't seem to be burning any white smoke out the back though, and like yourself my oil doesn't seem to be milky or anything like I would expect. Let me know if you find out what the cause is, and likewise I'll do the same.  

Unfortunately for both of you, you have leaking head gaskets. The only additional damage you can do is that your coolant could get so low that your vehicle could overheat. Even still, I wouldn't recommend driving it around much.

I see your Ram is a 2005. Regardless of your mileage, call Dodge customer assistance and complain of the problem. If you take it to a dealer, the company may cover at least a portion of the repair if you can prove all maintenance is up to date.

I am sorry to tell you this but this is a costly and time consuming repair.