Don't use any type of engine flush. What crud it doesn't break away completely, it will loosen. So you'll be driving down the road and this loosened crud become loose and plugs up your oil passages.

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member