The only time I had a leak was when a vacuum hose was inadvertently caught under the cover, and that was massive - as soon as I started the engine. The oil filter lid appears to run at the outlet pressure of the pump (~50 psig), so easy to get a leak. But, the technology of an O-ring captured in a groove as a "face seal" is a sound design and usually gives no problems even at 1000 psig. Check that the cover is flat and has no tiny cracks.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans