Several years ago Consumer Reports did an article on what oils worked best and did a side study on how long to go between oil changes. They ran NYC taxi cabs with identical rebuilt engines and opened the engines after set distances. They found no meaningful difference between oil brand. They also tested whether the interval between changes made a difference. They ran some engines 3,500 miles, some 7,000 miles, and one 12,000 miles. There was little to no difference between the engines when they were opened and the internal wear compared.

I think this is the article I was thinking of. Consumer Reports:Truth Motor Oils- July 1996

I went 10,000 km's on my Z06, the oil monitor came on. It used Mobil 1 synthetic. When my mechanic changed the oil he noted that it was pretty dirty.
Three weeks later I had a low oil pressure warning. Wound up with a broken main bearing. Probably a coincidence but I now change the oil at 5,000 k's.

Twenty five years ago there weren't nearly as many turbo charged cars as you see today. Turbos like relatively clean oil. I wouldn't go more than 10,000 miles on a modern small displacement turbocharged engine. I'd personally go 7,500 miles or less.

I'd be curious to see that same test run today.

That's a good point. A lot of turbos pyrolyze oil. But what if that modern small displacement turbocharged engine had a 3+ gallon oil system?

Point: Lubrication systems have many variable. Higher end cars typically have those variables held to higher standards. If you have a cheapy econobox with a turbo and 4-qt oil system with the cat designed up against the oil pan -cough SAAB cough- then you won't see many of those on the road after just few years - even with 3k oil changes.

But still, many other cars have engines designed for durability / longevity / low maintenance.

Usually I change my oil on all my cars yearly, putting in full synthetic and top quality filters. This year I got lazy with my 2002 W210 Benz and only changed the filter at the year mark.

It takes 7-8 liters of oil and I’ve only put 5,000 miles on it, but it’s been in there since October 2019.

Yes. It’s making me mildly anxious. Haha

Filter changes are typically the least effective thing to do. - notice how tiny they have become on modern cars.

If you want to know what your engine actually needs, do the oil sample analysis.

Taxi service should be low stress as the engine runs all day. I'd worry more if the engine was used for multiple short trips and never got to warm up.

You got me beat but the Boxster will go 4 years w/o an oil change. Reason? Well, not a good one but 4 years = 500 miles for this car. It's my wife's, not mine. If mine it would have been gone a long time ago.

2000 Normal 2.7 with 63,000. It was driven more in the first years. Now I get a few hundred miles and I need to buy a new battery. Drive or not, maintainer or not, they only last as long as they are planned to last. 10 years would be a record for me.

So to the question, the oil has been changed once in 10 years and that was 4 years ago. I use Motul.

But that was 25 years ago. Oil technology has changed a bunch. The synthetic that I use is made from natural gas. While the Fischer - Tropps process used to make this is not new, only recently has it become economically feasible. Additive packages continue to evolve as well.

My wife's Jeep during the busy season for her home building company, it often reaches 10,000 miles so quickly, I can't keep track (every 4 months). The car is rarely home before 6 pm, and she sometimes to forget to tell me.

That year was a 3.4l V8 with a Cosworth block and Yamaha heads.

I have run over 7000 miles at the longest and that was our minivan with the oil monitor telling us it was down to 30%.

Our truck says 7500 and I change it at 6500 or every spring, whichever comes first.

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1996-1999 they had the 3.4 double overhead cam V8. Mine is a 1997 model and it is a V8.

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The earlier were just a Yamaha V6, then the V8 then the turbo V6.

I would bet steady state cruising on the interstate is much easier on turbo charged engine's oil than a track day session.

Yep

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Dang, i do that in a month currently. Commute from Tulsa to Wichita a couple days week. Some days the whole damn state.

14k was my change interval on the 7.3 ford diesel per oil analysis I could have pushed it further, but didn't. That thing needed a lot of oil for one fill, so it was worth checking with analysis. On my current daily drivers it is all 10k change intervals with synthetic oils. The 993 yearly or a little less, if I don't drive it much or have it on the track that year. It has been a long time where i racked up more than 2k / year.

G

Tundra and Outback 10,000 km with Mobile 1 synthetic. Around once a year.
996TT (Mobile 1) and 86 Carrera (Brad Penn) once a year and maybe 5,000 km.

Keeping inventory of the oil/filters is the hard part as I do it myself. Too much crap.

Much of the oil change interval depends on how long you keep your cars. If you swap cars when they get to 80,000 or 100K miles, it does not much matter, 10K oil changes are fine.

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Look at the silicon trace. It would go up, I change the air filter, and it drops to almost none. That is sand and dirt sucked through the air filter.

For my El Camino, it came with a factory 305. It was smoking a lot after 300,000 miles.

This is the cam from that engine. All the lobes were fine, no wear at all. All those miles, and the inside of the engine had almost no sludge after all those miles. The valve guides were really worn, and the rings had wear.

The machine work on a 305 is more than it is worth. I just put in a brand new 350. Not rebuilt, not remanufactured, brand new engine for $1,700. I did it myself over the long Thanksgiving weekend.