I have a 99 Cummins with 109,955 miles on it. I have noticed I had white smoke coming out of the blow by tube but not anything noticeable unless im stopped for a few minutes.  if I take the oil cap off it blows a little white out of it but not like clouds of it.  So next I did the oil cap test and removed it and flipped it upside down and it didn't bounce around or move (except a little due to vibrations of the engine).  the truck runs awesome no lack in power perfect pick up and go, it doesn't smoke except a little black on start up and doesn't eat coolant or oil.  No knocking either.  The oil pressure is around 30-35 at idle and at normal cruising speeds of 55mph at around 1800 rpm its around 40-42 and the temp never rises above 192.  my question is, is this normal im new to Cummins and should I worry

If the sun is right, I can see my vent mod smoking while at a stop light. Looks like michael's. I suppose that plugging the vent tube would be necessary to get a real look at blow by at the oil fill cap.

Never plug the tube even for testing it's not done for any reason.