That repair is common failure on these engines N62, it is well known issue that after aproximately 150000 miles the Alternator bracket gasket starting to leak, it could leak years but soon or later it will get big and it will start to leak really bad. The car I bought recently from USA had that issue, when I started the engine it was leaking almost like a small flow, the gasket was so bad... that for few hours of idling could drain about 2-3 liters of oil! I know that repair is not easy, to do but if I can do it, why not you?? It is quite expenssive repair, the gasket cost only few dollars, but the repair worth between 1000-1500$ if you send it to a car repair shop. It is a straight forward DIY process, and it takes about 2 days of your time to do it. See below my DIY job on my BMW 👇👇👇.