I'd be curious to see a lab analysis of oil used in a modded T1 engine. Oil now is definitely better than non-detergent 30W running thru a T1 fly screen filter. I still remember the oil ad: "pay me now or pay me later; oil is cheap, iron is not"
FRAM introduced its iconic slogan, “You can pay me now, or pay me later” in 1970.
I used to change my oil dino oil and dump it on the loose stone driveway of my parents house! Don't tell EPA - hopefully the limits of prosecution are long passed.
I change my own oil (still). On my new cars with full synthetic oil I go 1 year or 10 thousand miles. I suspect I could go 12-15k with hi-end oil and filter now that I'm out of warranty.