I came across an interesting article comparing modern full synthetic oils to conventional ("dino") oils. The most important takeaway was the need for frequent oil changes, regardless of the type of oil. Here are the comments: "I did a comparison of a very old oil formulation (SF quality from the 1970's and 80'2) to SH quality from the late 1990's and Mobil 1 full synthetic along with other full synthetic oils. After 100,000 miles the then modern oils protected the engine well enough, but there was minor differences in wear and engine sludge/varnish deposits, but nothing that would have prevented the engines from running longer. The old oil formulation which had 1/4 the additives of the newer formulations was tested at the then current 3,000 mile drain interval. What we saw from that comparison test what that the old SF oil with short oil drain intervals outperformed all the modern oils at long drain intervals. The engines were cleaner, has less wear, and used less oil than any modern oil formulation, mineral or synthetic. The lesson learned is that it doesn't matter what quality of oil you use, what matters most is changing the oil regularly."