In the first serious trial of my 911 SC "project car" at Fontana last week, I developed an oil leak that got me black flagged. I can't tell exactly where it's coming from; the oil is clean and it's harder to trace. With car on lift, it looks like one of these: left side lower valve cover gasket, left rear chain cover gasket, or a left side oil return tube (head to crankcase). It is a very slow leak around town (and on the way back from Fontana), a drop every day or so, and thus hard to pinpoint. It must have leaked more at sustained hi rpm and blown around at hi speed. I had just changed from 10-40 to 20-50 oil before the event, and after this I noticed the oil pressure was a little higher when the engine was cold.
Which of these areas (valve cover, chain cover, or return tube) sees the most increase in oil pressure at hi rpm?
Could left side leaks be worse due to the repeated right turns on the Fontana course?
To change valve cover gaskets, do I have to drain oil first? These gaskets were fresh from a valve adjustment when the engine was out, but I did not change the nuts or washers (Pelican recommends this). Can it leak around the nuts themselves if you don't change them?
Thanks for any and all wisdom.