Hacker News Reader

Comment by Timothee | Hacker News Reader

I discovered the engine oil thing in the past two years.

In the US, I’ve always heard something like every 3 months or 3,000 to 5,000 miles. The cars even warn you in that timeframe.

In Europe, a mechanic was very confused when I talked about an oil change when one was done the prior year. He said it’s more every 2 years or 20,000 to 25,000 kilometers. Once again the cars were set up to warn at that distance.

I’d love to get to the bottom of it. Why such a difference? I can understand the garages wanting the extra business, but why would the car manufacturers go with it?

View on HN

In this case I think the times have changed but old advice has stuck. From my understanding, cars until the 80s or so did need their oil changed this often, but newer cars with EFI and especially if you use synthetic, its no longer necessary to do so. Its been many years since I bought a new car, but IIRC even the mid 2000s you were supposed to get an oil change relatively soon after getting a car as fine particles that weren't entirely machined off should have been worked off in the first thousand miles or so and you were told to get an oil change then.

There is also the case of changing oil for hot and cold seasons- getting thinner oil in the winter and thicker in warmer weather to adjust. I think thats more or less a thing of the past as well, my Honda does not specify/recommend this in the owners manual but perhaps some cars do?

Old adages sometimes stick around forever though- especially when there is money to be made in keeping them alive.

Remember that the manufacturers recommendations are designed around keeping the car operational through whatever warranty period they sell the car with. It's not some sort of ideal program and some benefit exists from changing fluids more often than specified.

Specifically, transmission fluid is often considered 'lifetime' fluid that doesn't need to be changed, and, if you follow that advice, you end up replacing the transmission, an expensive endeavor, whereas if you don't, you can typically double its usable lifetime.

You also have to be careful about engine oil, because the margin of error is very small. Most modern cars have an oil minder, and those work well provided the oil itself is in spec.

>Old adages sometimes stick around forever though- especially when there is money to be made in keeping them alive.

Don't forget to make your swap space double the size of your ram!

Free oil changes from dealers are often offered on new cars. Getting you in to the dealer more often may benefit them in some ways:

1) Opportunity to upsell other services,

2) Some people (quite a lot, actually) have alien-to-me car buying habits and might be convinced to trade in their new car after only a year or two and buy another new one if you can just get them into the dealer at the right time.

No clue if that’s why they do it, but maybe.

FWIW, every time I've had my oil changed at the dealership (dozens of times, but only 3 different dealers, so take it with a grain of salt) it's always been done by the service department, with no interaction from sales at all, and therefore no upselling or discussion about trading.

Modern Toyota engines require regular oil changes because their tolerances and oil are very thin. You certainly can run them with far less but they won't last nearly as long

Oh if only it was that easy.

Those extremely long intervals will only work for cars that travel long distances, where the engine has a chance to warm-up and burn off any residual gasoline that gets in the oil during cold starts. If said car spends most of its life in a city, doing short trips, the oil gets rapidly dilluted and loses the ability to lubricate the engine properly.

Most modern cars will take all this into account when trying to determine when the next oil change is due. Also, manufacturers nowadays usually specify shorter intervals (6 months or 7500km) for modern direct injection engines that only drive in a city.

Reply on news.ycombinator.com