Yet another update. I finally broke down and used a commercial oil additive to slightly thicken my oil and increase viscosity. Lo and Behold... the Check Engine light as stayed off for several days. My mechanic, after all this, said he didn't think it could be an oil related issue because I had recently changed my oil. It looks like we may have spent over $300.00 for nothing! The additive I tried was recommended for "high performance" engines and the clerk at Auto Zone. At the rate I expect to use it, I now have a two or three year supply!
