I change my oil at 4000 miles since I started driving, my dad said 2500 but I went 4000 or March July october Jan, never had any issues I drive a car for 10 to 12 yrs, I'm poor so oil filters don't really matter a lot but I use AC delco, KN fram, it never has time to get dirty, Tractors get every 100 hrs, grain farmers once or twice a yr
lol . . . that's really old school, changing 4000 miles or less. That used to be the way to do things 40+years ago. But with oils today with all the additives, oils can easily go 7000 without a need for changing. Of course, good filters are a factor as well.
Back in 1974 I started using synthetic oil as it had recently came on the market for automobiles. I first because aware of synthetic oils when I started working on aircraft and learned a lot about the befits of it. It was after a study was done where Mobile 1 was used in a fleet of police patrol vehicles for 50,000 miles, the engines were torn down and inspected for wear. Almost no wear was found. That's when I decide to go with synthetic, especially since I had turbo charged my cars. From that time in 1974, I started using synthetic oil I've changed oil every 25,000 miles, but because oil filter aren't designed to last that long, I'd only change the oil filter every 10,000-12,000 miles. Another nice benefit, was the engine burns less oil using synthetic and runs cleaner (emission control test people have always been surprised by how clean my engines run). These days, there are filters designed to go 20,000 miles for optimizing the use of synthetic oil. So, now I use a Fram oil filter that does that and I only change the filter for between 15-20K miles and will do a complete oil change at 30,000.
Though synthetic is the way to go, it's initial cost is more, but the way I use it, I figure is actually costs me quite a bit less. I've currently got a 17 year old SUV with 203,000 miles and not had any issues at all with it. The engine runs like a top.
Funny, back in those early days in the 70's, I'd go into an automotive store and ask if they had any synthetic oil and I'd get crazy looks . . . like, what are you talking about. One guy looks at me an not joking replied "we only carry real oil here."

Back in the 80's there was the Rutan Voyager aircraft that flew non-stop around the world (no midair refueling). And as I recall, they were using Mobile synthetic oil and sprung an oil leak near the end of the flight resulting in essentially no oil in the sump. They finished the flight with no oil pressure and the engine didn't seize up. The non-real synthetic saved their record flight.
