I have used napa filters exclusively since I have ever owned a Mercedes. I have never had a problem.

Also one thing to consider is petrolium products can cause rubber gaskets to swell some. So the O-ring your replacing being slightly thicker than the new one isn't definite proof of a problem. Not sealing is definite proof however.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

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