I could go long and get into the complicted logic of wear and purpose and additives....et al.

Instead consider this when trying to calculate the value of oil changes.

Which cost more over the 150K to 200K miles expected life of the engine, the oil changes.....or the engine?

Change it at 6 to 7 K miles like the manual says.

And at least once a year. Whether it needs it or not.



roadster with a stick