I saw yellow liquid at the bottom of the alternator a month ago and wiped it off. I saw it again today.

I do not think it is leaked out engine oil, because engine oil in my car is black.

My car is 1992 300D.

__________________
1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.