My son’s 2008 E320 was consuming oil at the rate of about a quart every 1500 miles. Bottom was wet and the tail pipe dry (not oily, just a very light soot) so it was a likely a leak. 235 k miles and counting.

Things I did, it finally took doing all of these to get it to stay dry. It’s been dry for the last month and probably 1000 miles and level hasn’t moved off of full.

Oil filter tower - replaced both the tower to head and the mid of the neck gasket. There’s a Dorman kit that has both gaskets.

Crankcase breather puck. If the diaphragm is torn it sucks oil down the turbo.

The adapter on the back of the right bank cam the breather plugs into. The seal gets old and lets oil blow by into the breather.

And finally the oil cap! The easiest fix of all!

I did replace the turbo about a year ago, not sure how much that played into it. But since I wasn’t burning it I am not sure.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech