1999 BMW 540i Q&A
1999 BMW 540i Question: oil leak around the oil filter , .
Check your filter for tightness and if that doesn't fix, replace it and do an oil change because if the oil filter is overtightened it can damage the rubber seal. - jason94
You must replace the rubber seal in the cap every time you replace the filter. It will harden and flatten over time. No amount of tightening will fix this. The rubber seal (large O-ring) is located just above the threads on the plastic cap, if it's not obvious (already flattened). - RNCLS