Because it costs significantly less and not every engine needs synthetic.

You say “period” but don’t use a period. Interesting.

But just so we’re clear, synthetic oil is still petroleum based. It’s just processed more. Which makes it more expensive. And money makes the world go around.

Synthetic oil is roughly 35% more expensive than conventional (depending on sales obviously). And if people are going to change their oil every 3,000 to 5,000 miles, no matter what, it’s not incredibly beneficial to run synthetic anyway.