2002 Blazer Oil Leak - Rubber plug?
 

Just got this. Runs great, but has oil leak.

Was going to clean it when I noticed this rubber plug. What is this? Somebody said it's factory and maybe not needed? Likely not the issue, but any suggestions on how to best find the leak?

It's got 196k miles, any recommendations for things to look out for before I make any kind of investment in it?

Thanks!



https://drive.google.com/file/d/0B_0...B3ckJQV1E/view