You tighten the main bolt more, but don't go too far, you could crack the filter mount. I had a leak form the bolt it'self that tightening would not fix. My indy. said that overtightening could crack the aluminum mount. The fix for my problem was a new bolt.

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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