Motor Oil Age Doesn’t Matter as Much as Mileage: Study
 

https://www.thedrive.com/news/motor-...-mileage-study

I've never heard of 6-month oil changes. But I do subscribe to yearly ones. I do, however put some miles on all the cars. Usually at least 2,500 or so.

I've always said this. If I don't accrue enough miles, I'll go 1.5 years on synth. I could see stretching to 2 years, for under 4k miles. IIRC, my 06 cayman S specified 2-year intervals. I also see no reason to dump gallons of still OK oil back out into the world. Come to think of it, I'm not sure where those go, something to google.

All that said, during my e46 m3 search a decade ago, I came upon a car that was Imola, pristine with 14k miles or so and local-ish. The catch? This 05 or 06 car, had its break-in change and then again a change in 2012 at 12k miles (roughly). I was like "How is this ok?". Seller got testy and said this is what the car's computer told him to do. Later ended up at that overpriced Ohio m3 seller, selling for big money...

Motor Oil Age Doesn’t Matter as Much as Mileage: Study
 

Ugh. I think (memory getting worse these days) that the E46 service indicator was only mileage based (miles/amount of fuel used). They added the time-based alerts in later models, believe the E9x and later.

Speaking of - my M550 was due for an annual service based on time only (still short on miles) in March. Now that we’re in April, I start getting a nasty “your engine might explode if you don’t service the car immediately” type message on start up. Annoying enough that I’m getting the oil changed today, so I guess it did its job. 😁

"Squeaky wheel gets the grease." In this case, almost literally.:D

Whoa!

When our car and truck dashboards say 25% life left, I change it

I still run the simple calculation cutting recommended mile interval in half or once a year whichever comes first. Unless the car is driven very little, like 2k miles/year, in which case I may go 18 months.

Actually put on a bit more mileage since last oil change than I thought - 9k miles, service indicator said 2k left. Anyway, car is all refreshed & up to date - oil, brake fluid, air filters & microfilter.