I decide to see how much carbon has accumulated on my the EGR valve, a 2005 TDI-PD. I had installed the Provent CCV filter at 4600 miles, now the car has 7800 miles. As expected the EGR valve had a thin layer of black carbon. After cleaning it up I checked out the intake manifold by looking down the hole where the EGR valve goes. Also as expected there was a thin layer of matte black carbon. The carbon looked dry but I then pressed my finger onto the manifold wall and I found out the carbon was moist. I was expecting the carbon to be dry, like what I found on the EGR valve. I know the Provent filter is working well as the clear tubes exiting from the Provent are oil free. At the time I probably should have tried to determine if the moisture was water or oil based. It was just black goo. So any ideas why it was moist in there? I'm beginning to think the Provent CCV filter is not going to prevent intake manifold clogging.