I stopped at the Shell station one day off the 94 in Tonopah Arizona, Guy was there in the parking lot with a bunch of tools and I asked him if you needed help with anything, he said no just changing my oil! I didn't want to know what he was doing with all his old oil.
I know of a guy who used to take used oil from guys who did oil changes every 250 hours and run that oil another 250 hours in his truck.
My dad had an old Chevy that used so much oil, he quit wasting money changing it...just had his friends bring him their old oil they drained from their own cars and he'd add it as needed to his old truck.
A lot of people who change there own oil will dump the old oil in the fuel tanks. Seen it done many times. Not sure how that may affect some of the new trucks.
In the early 90s I bought my wife a new dodge 4x4! I used Mobil 1 and would drain it at 5000 miles and then use it in my old jeep. I would buy the oil and filter for her truck and filter for my jeep every oil change.