Thanks to all of you who have responded. The car is a 1991 with 148K. I did, as one respondant suggested, listen for the noise with an automotive stethoscope and it seemed like the noise was coming from the smog pump...hence me replacing it. However, as anyone who has done this before realizes that noise does travel and it is hard to pinpoint sometime. The oil line reference makes sense. Is there a solution or do I just live with it? Thanks again for your suggestions.

antonino