06 5.9L Down cylinder?
 

When you take off the oil cap there is an inordinate amount of back pressure. I was told by one mechanic that it must be a broken ring. Also it is idling rough and there is alot of crankcase pressure venting through the tube. Is there anything else that would cause this?
180,000 miles.

my 05 did the same thing tore it down and i had 2 cylinders with broken rings. after rebuild with all new pistons, rings, etc. i still have the exact same amount of blow-by.

there are blow by meters to determine just how much is too much...

Ihave also used 1 - 2 quarts of oil in 1000 miles.