[georgerobinson]

It's interesting that a lot of readers here and websites in the U.S are saying oil changes every 3,000 or 5,000 miles. This is absolutely not the case in Europe where most cars are on 10,000 or 20,000 mile intervals. I wonder if this is due to much more diverse weather and temperatures you see in the U.S throughout the year and so different grades of oil are required that degrade much faster.

[tristor]

Manufacturers are pushing to extend oil change intervals but depending on your climate and driving style you’ll see different oil degradation, and it had nothing to do with differing quality of oil. Oil standards are international.

The only way to know is to consistently and regularly have used oil analysis done. For my part, I change my oil every 3k or sooner because my vehicle gets put on a race track occasionally, which changes wear patterns and an oil change is cheap insurance. For full synthetics on a car which mostly sees highway miles 10k intervals are fine, but 15k and 20k intervals are ridiculous. For most cars in the US which see significant traffic a 5k interval is correct as stop and go traffic is actually harder on the engine than almost anything else.

Side note: A kilometer is just a little over half a mile. A 10k KM OCI is equivalent roughly to a 6500 mile OCI. So there isn’t that much difference between the US and European intervals.

[Zach_the_Lizard]

My last car said 10k miles in the owner's manual, but every time I got the oil changed the dealership would always lie and say 5k miles was recommended.

Maybe that was true decades ago, but it's no longer true. They prey on the misinformed. To be charitable, maybe they know many people wait too long, but I doubt it.

I went every 10k miles or so.

Other cars can go longer distances without an oil change, as you say.

[prolepunk]

I think you mixed up the units here.

In us oil changes are 3k-5k miles. which is ~5k km to ~8k km whereas in Europe it's 10k to 20k.

I find 8k-10k figure to be close enough and realistic.

5k km for old cars with non-synthetic oil.

20k km I highly suspect is a pipe dream from BMW marketing material ensuring that after about 120k the car would have no resale value.

[incog-neato]

Some oil places just straight up tell you a lower number even when the owner's manual of the car says a higher one. I just go with what the manual says, rather than some random Jiffy Lube employee.

[dsfyu404ed]

I tell people to just change it on the 5s because that's an easy round number and an engine that burns/leaks a little probably won't run out in that time. For synthetic I'd say 10k.

[free652]

I am using my Honda's computer and it asks to change oil around 4500 miles mark. I am mostly drive in a city, so that's would be a cause. I know for others the computer uses more than 10k intervals.

Full synthetic oil/filter is about $60 to change here.

[imglorp]

I don't know the cause either but if you look at your oil, you can see it gradually turning colors, from pale ale to stout. At 5k in the US you're about at the latter, so I'm inclined to believe they're telling the truth.

[georgerobinson]

As I replied in another comment:

> Oil changes color as it captures contaminates such as soot, carbon deposits, etc. It can operate effectively while brown-ish, but if the oil is carrying too much it will blacken and start to thicken at which point it will be much less effective at lubricating your engine.

[xfitm3]

Odor is a better wear indicator. It'll smell burnt when it's ready to be changed.

[ljcn]

I heard it is a hangover from the days of using mineral oil.

Modern synthetic oils last much longer.

[mywittyname]

Synthetics last for so long that the breakdown of oil is not really a concern anymore. The primary reason to change a synthetic oil is due to contamination.

Modern engines are designed with much, much better tolerances than before and crank cases no longer vent into the atmosphere. If you use new synthetic oil in an old small-block Chevy, the oil will hold up for a long time, but it will be so contaminated by gasoline, moisture, and debris that it will still require shorter replacement intervals.

[dboreham]

It's due to people wanting to make more money, and succeeding.