I have a noob question... I was changing my oil today and noticed that there was a bunch of gunk built up below my oil filter. The filter itself was not leaking oil.

Can anyone look at the picture and tell me what's going on?

Thanks in advance

 

the bunch of gunk near the oil filter could be from the following:

1. oil that spilled during previous filter replacements and has accumulated and mixed with dirt.
2. leak in the differential oil seal.
3. was the drain bolt tightened snug tight? how was the washer on the drain bolt? if the washer is already crushed/damaged, then it needs to be replaced as that could be a source of oil leak and the oil spread while operating.

 

Other ideas:

Is, if there is one, the oil cooler leaking? It's a canister mounted to the engine near the oil filter.

Real bad valve cover gasket leak?

Get some degreaser and go to town cleaning it up and see where it comes from next. Unless it's something super obvious, with that much gunk under there it may be hard to tell until it's cleaned up.