This is a couple possible causes. First it could be the rear main seal. This is the seal that goes between the transmission and engine and seals around the crankshaft. The other main thing is the oil pan gasket but if it appears higher then that, I suspect it is the rear main seal.
https://www.2carpros.com/articles/crankshaft-main-seal-replacement-rear
What happens is when the oil drips down, it gets blown back while driving and can get everything behind it covered in oil and then the dirt sticks to it.
The way to confirm this is to clean off the oil and dirt then add some dye to the engine oil. Then drive the vehicle and inspect for the dye to see where it is coming from. If you don't see dye but you do find the oil, then it is not engine oil. However, based on what you said, I am pretty sure this is your issue.
Let me know if you need more info. Thanks
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Mar 14, 2020 at 7:41 AM
