In 1970 my brother bought a plain Hillman for $200 and drove it for 40,000 miles without changing the oil. He was adding quart once a month.
At that time I had a flashy $450 MGA and put Pennzoil racing oil in it and changed the filter every 2,000 miles. I got 45,000 miles out of it before it was destroyed in a collision with a drunk driver.
In the end it did not make any difference, but we lead the kind of lives we wanted.