Teflon is made by Dupont. Dupont's engineers said that Teflon was never meant to be used in an internal combustion engine. The one of the many claims of Slick 50 is that it puts a "protective coating" on all metal parts. Let's think about this. Your engine has many small oil passages that are designed and drilled to be 'X' big. Now you go and add this "protective coating" you now have made that oil passage a little smaller. If the engine engneers wanted the passages to be that small, they would of made them that small.

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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