Sounds like a valve job to me. My 560SEL had the same symptoms. Looked worse than my diesel when taking off the line and for the next 1/2 mile.

Mine started consuming 1qt/250 miles and degraded to 1qt/100 miles

Mine required a valve job and replacement of all valve guides.

Aside from the tools it cost about ~$1500 to DIY, from a garage expect between $4,000 to $6,000. I also did some other preventative work while I was under the hood.

Where are you located?

Good Luck!


Scott