I believe the trick on the 606 is to never fill it completely. I usually leave it 1/2 way between the full and add oil mark. Often I do not have to add before a change. Over 200K on the engine.

KarTek I had the same symptoms when I first purchased mine and ran a can of KANO Kreen through it for a week of very light driving just before an oil change, I would say it nearly eliminated the concern,

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250, Dec 2024 145,000 miles