After I read river rat's reply, I realized that I have been using 5 year old plus oil in my 91 Buick Park Ave and 79 Chev Van for a long time. When oil was really cheap with rebates, I bought cases of any brand, in which a lot of it was less 50 cents a quart.
I had to drop the oil pan on the Buick when I had to replace the sensor button on the crank shaft timing gear 4 years ago, finding that the pan pristine clean: absolutely no residue and no wear of any parts that could be examined. The car has always used 1/2 to 2/3's of a quart between 4000 mile oil changes since new with 192,000 plus miles,now.
I have done hours of research on this since my post with the same consensus on synthetics:self life "is" 5 years.Regular oil based stock is well past 5 years if the container is not paper,has never been opened and has not been stored where it has been exposed to real low and real high temperatures. This stuff came from regular home mechanics,car shop mechanics,heavy truck-equipment mechanics,mechanics from branches of the military, airplane mechanics,etc.that regular oil has a long life.
But as always it comes down to what one is comfortable with.
I'm finding this forum very informative on many things.