Hello knowledgeable Porsche friends. Today I was replacing the alternator on my 2002 C4S manual. I was fortunate enough to get the alternator out without too much of a struggle, but once out I could see oil pooled on the top of the block in the depressions. It is dirty oil so I am not thinking a cracked oil filler tube. Pictures are attached. Has anyone else encountered this and what might be the source of the oil? While the alternator is out I might as well attend to the source. It has not leaked enough to be noticeable on the dipstick or drip on the garage floor so it would seem small (but maybe not “minor”). Thanks in advance for your comments and advice.

Overview with alternator removed.




Closer view of the pooled oil.


Many thanks again.
Cross posted

 

On my 99 c4 this was the seals between the oil cooler and the block. I also had some antifreeze showing in the same area.
I drained the oil and coolant, put a shop vac on the expansion tank to pull some vacuum (it is an oil to water cooler :-)). On my block the seals where 2 different sizes. I managed to avoid any cross contamination somehow
120,000 miles later and still tight and dry
This was in Nov 2012 so what I remember is vague, except for how cold it was :-(