I purchased my 1989 VW Jetta new and changed the oil in it every 2000-3000 miles, sometimes even more often. I drove it for 225,000 miles over 11 years. I sold it to a friend who is still driving it at now over 260,000 miles. It's never burned a drop of oil, never had an oil related problem or even any engine related mechanical problems. I used 20w-50, typically Valvoline AC or a store-brand Valvoline dino.
So in my real-world experience, while test run on engines in controlled environments or engines that never get shut off may produce less wear as oils age, i think that wear as measured in test alone is not the only issue. Deposits, sludge, dilution, and keeping the oil level at spec are all important. Perhaps a lab can show me that leaving my oil in longer than 3,000 miles produces no "more" wear on that specific UOA, but i dont accept that changing my oil earlier will somehow harm the engine.
I wonder if the oils ability to absorb and keep contaminants suspended was measured? Doesnt it make sense that as the oil ages, it gets "full" and thus no more wear can be measured past a certain point? Clean oil likely "absorbs" the most crud from your engine, which is why a sludged up engine can benefit from multiple rapid oil changes done at 500 or 1000 mile intervals until the engine cleans up.
I've seen and read of lots of folks sending their engines to an early grave by not changing their oil. I've never heard or seen an engine that was sent to an early grave by too frequent oil changes.
