thought I would bring this up from the dead...I switched to Mobil 1 Synthetic Oil back in March '03. thereafter have used the same oil at every change:

There have been many discussions as to whether or not a synthetic oil would be a good thing for the SVX. In the matter of speaking I really think synthetic is the way to go. However, I still have some concerns and have noticed a few occurrences during this aggravating 6 month period:

I started getting oil leaks on the front and rear seals after about 1,000 miles. Now the leaks have stopped, I’m getting leaks on the sides of the valve covers. The leaking seems to go in cycles. ?? Has anyone experienced their oil leaking in cycles?? I was told that the leaks and swelling should stop over time. In the meantime it seems to be a concern, and more of an annoyance of where the oil ends up. Some on my spark plugs boots and some on the exhaust pipes (near my oxygen sensors). I'm constantly wiping off oil from other engine locations (not to mention the my garage floor). Anyone else have any insight on synthetic oil. Since March I have put maybe 6000 miles on the car. I was changing the oil every -2000-2500 miles.