I walked out to the rig (07.5 Dually) today and noticed a small puddle of clear looking liquid. Close inspection revealed the source, So what would cause this valve to drip? It's at the bottom of the radiator.

 

Where do you live? Is ice possible? You could have had ice somewhere that melted and dripped to that point, or your HVAC drain could be making it that way for some reason or another. No clear liquids that I know of in our trucks...

I would also assume that is your petcock...

 

Ya pitcock... Had a brain fart... I hear you on the clear liquid part. I first thought brake fluid but nope it's pooling right below the pitcock pictured.

And yes ice been in icy/cold
areas around NE Texas/SW Arkansas. So MAYBE, However the rig has been sitting for a day. Can't be condensation? Plus the puddle has a slightly slick consistency to it.

 

It could be. I'm sure there is plenty of grease on the rad for it to feel sticky.

Pure Ethyl Glycol is clear and slightly slick...