Need some ideas

[Black 535i]

I have noticed over the last few days a puddle of fluid under the rear differential cover on the ground in the garage. Is this a usual area of leakage and what may it be a symptom of? There is no other areas that are leaking under the car anywhere. Is it just a gasket issue? I honestly have not changed the dif fluid in 45,000 miles. Can this gasket be changed easily by one's self if that is what it may be? Thanks in advance for any help.

[Blitzkrieg Bob]

I'd degrease the diff, and see where the oil is coming from.

I doubt the gasket would leak, most likely it is one of the out put seals on the sides.