Interesting to say the least. After 30 years, I left the automotive field in 1999. I have made it a point to not stay informed.
For me, the biggest improvement in oils came around the mid to late seventies when we started getting away from Pennsylvania based oils. Too much WAX! Boy, when you took an engine apart from someone who was a Quaker State or Pennsoil fan, you had to evacuate the shop for the burned wax smell to dissipate. Blended motor oils like Mobile and Castrol showed a superior performance with little to no wax build up. Those running the high wax oils often had a 1/2-3/4" buildup on all the metals. Before you ever started washing them with a solvent you tried to scrape as much of that crap off as you could. To help reduce this, we would often suggest to our customers that they add a quart of tarry fluid or Marvel Mystery Oil a day or two before their oil change and make sure the engine was running for at least an hour or two before they in. Synthetics changed all that for me and I have been a fan of AMSOIL for a long, long time.
Most people don't have an idea what the 5W-30 means on the side of the oil can. They see it as really "thin", but at operating temps it has the same viscosity as simple 30 weight oil. 30 weight non-detergent (no-additive) oil was what we ran in the most extreme machines like a roundy round car or a dragster. Too much viscosity and the oil pressure went HIGH with less oil being distributed to all the parts. Less oil is never a good thing.
That being said, we used to have to change tappets and cams a lot more in the old days (pre 1975). We did more valve jobs and overhauls too. My Honda Ridgeline has 190,000 miles on it and I have only had to change the plugs once (130,000) and the timing belt with the water pump (150,000). I did break a spring on the side of a mountain in Utah, but all I have done other than that is to change oil, brakes and tires. That type of benign neglect was a recipe for disaster even through 2000. Most people can't even feel her idle. Of course there is ONE problem. The Cat stopped working @ 100,000 miles causing the Engine Light to come on. I reset it now and again and check that this is the ONLY problem. Maybe using something OTHER than Amsoil would have prevented that?