I've read thread after thread about similar issues but none that give me a solid answer so I'm trying my own. '08 6.4 powerstroke fully deleted, H&S tuner, 120,000 miles. I'm having an issue where i have light to moderate blue/white smoke from my exhaust but it doesn't happen all the time. Only when it's at operating temperature and at idle. Once im up and moving it either stops doing it or i just cant see it at speed. The first time it happened I didn't drive it for a few days and then drove a week with no issues at all. Over the last month its done it every now and then but not constant at all (of course i only drive it 20-25 miles a week these days), if i shut it down and let it cool off it quits the next time i start it. I don't have any other issues at all with the truck, no missing or rough running, no loss of power, no weird noises, runs like a top just blows embarrassing blue/white smoke at stoplights sometimes. If i catch it doing it and pull the oil fill cap off the smoke slows down and stops, just blows out of the fill cap instead and doesn't seem nearly as bad, just sitting there idling it wont start back coming from the pipe after i put the cap back on. The blow by "test" with the fill cap seems fine, flip the cap upside down and it wont lift it. Stock CCV to S&B intake, the CCV hose is clear, I thought maybe turbo seal but the downpipe is dry, i don't appear to be losing oil or coolant. I really dont want to admit it but the only thing i can think of is I'm losing compression on a cylinder, but again i would think that would be a constant thing and that i would be able to tell a difference in how its running. I have a buddy coming with a scanner tomorrow to see what i can see, I'm just hoping someone here can give me a direction to look in, preferably a direction that doesnt lead to a new engine. Thanks guys.