How frequent oil changes for newish car

Factual Questions
1

I turned up a couple of older threads, but was wondering if current thought had changed any, given newer cars and synthetic oils.

I have a 3+ year old Subaru Forester. I put <6k miles on it per year - probably just about even between city and highway. They recommend oil change/service every 6 months. I’m past the 3 yr but still in the 5 yr powertrain warranty.

While the care is/was in warranty, I kept up with the every 6 months, but now I really wonder whether I could go down to every 12 months. WHat do you think?

I doubt I’ll drive this car into the ground. In the past I’ve traded cars in after maybe 7 years. But who knows - at my age (64) this car might out live me!

2

Wanna’ put some science into the answer? Send in a sample of your motor oil for analysis – say, at 3mos, 6mos, and a year:

[or equivalent]

Everything else is a guess – educated or otherwise :wink:

ETA: a thread about the better oil analysis options:

Favorite Oil Analysis Provider – Bob’s the Oil Guy

3

When it comes to oil change intervals, the two most important variables are miles driven between oil changes and time between oil changes, with the former being primary and the latter being secondary. What does the manual say about miles?

At any rate, a good rule of thumb that has worked well for me is to change the oil & filter every 5000 miles or every 12 months, whichever comes first.

4

What actually happens if you don’t change the oil frequently enough? Does it hurt the car somehow or just make fuel economy worse, etc.? Why don’t cars have built-in sensors for this like they do for everything else?

5

Old oil can hurt an engine, for a number of reasons:

  • Gasoline gets into the oil. Gas is not a good lubricant, and it decreases the viscosity of the oil.
  • The additives (detergents, etc.) in the oil break down.
  • Solid particulates will accumulate in the oil.
6

All engines have an oil pressure sensor. Some have an oil level sensor. A more sophisticated (and reliable) oil sensor would be very expensive, and not needed if the owner simply changed the oil & filter on a regular basis.

7

I see, thank you. I better go change mine!

Hmm, makes me wonder what else I’m neglecting. Probably a lot! I don’t pay attention to things unless a warning appears (like low gas, tire pressure, wiper fluid, etc.). Cars seem so reliable these days that the idea of having to do regular maintenance outside of the warning lights seemed… archaic? But apparently not?

8

Modern cars are supposed to remind the owner of PM items, and (sadly) a lot of people ignore them.

Yes, please change your oil on a routine basis. Make it a priority. You will thank yourself later if you plan on keeping the car for a while. And if you plan on selling it, there’s an ethical component… if you’ve neglected to change the oil, you’re screwing over the new owner. (I once bought a Toyota from a woman who claimed she kept up on oil changes. I learned soon enough that it was a lie. Ended up rebuilding the engine.)

9

It’s been semi-regular, every 6k-10k miles or so. Is it sufficient to disclose that, or should it be a big red “oil NOT changed regularly” flag? 10-year-old Subaru Crosstrek – probably similar engine to the OP’s. Seems to be fine so far.

10

Only 6K per year? What percentage of the time are you driving at operating temperature because if 90% of the time you are driving 10 minutes to the grocery store then there is a different answer than if you are driving 500 miles round trip once a month.

Also, I wouldn’t keep conventional oil in my car more than 6 months no matter the mileage. Synthoil a year at most.

Filters?

11

The manual says WAY more miles than I drive. For example, 3 yrs/30k miles. I barely drive half that.

Not too high. A couple of times a week I drive 4 miles to/from work. A couple more times I drive <10 miles to/from music and golf. 1x/week I drive maybe 10 minutes on highway to more music. Then a couple of longer - couple hundred to couple thousand mile highway trips.

Yes, I understand that. And I’m not suggesting I NEVER change the oil again. I was surprised when I bought this new car and it said every 6 mos. IIRC, my 29017 GTI was only every 12 mos. For whatever reason, I had thought 1 yr/10k the standard. I was wondering what the realistic risk would be if I did synthetic oil yearly? Sure - something crazy might happen. But how likely? Other crazy things might happen no matter how often I changed the oil.

12

Check your manual. But I would think you’re O.K.

As mentioned above, I change mine around every 5000 miles. That’s premature according to many (most?) car manuals. But I consider it cheap insurance. It also allows me to occasionally “go over a bit” if necessary (e.g. 7000 miles) without worry.

13

I go by the earlier of mileage or time that is in the manufacturers schedule. My last five cars have all had an indicator on the mileage that comes on 500 or 1000 miles earlier and the dealer puts a sticker indicating the 6 month or 12 month date.

Seems like most cars nowadays recommend synthetic oil that can easily go 12 months.

14

I think you will be fine with annual oil changes. Though my 2010 Honda Fit has an oil percentage usage indicator on the dash. It’s at 100% immediately after an oil change and drops over time. At 15%, I get a request to get the oil changed.

15

That is the hardest type of driving on an engine.

16

Keeping up with the factory recommended interval for fluid changes on a car is going to be the single best thing you can do to keep it running for a long time.

As mentioned, oil will eventually get bad at its job of lubricating the moving parts of the engine. Let it go for too long, and sludge can form which clogs oil passages, preventing oil from getting where it needs to go, leaving surfaces oil starved, and ruining the engine. Even routinely putting it off too long can cause excessive wear and premature failure.

Look in the owners manual (almost always available online), and just follow the recommendations in there. If it’s 6 months or 5,000 miles, then do the changes at that interval. If it’s 1 year or 7,500 miles, then that is the interval to follow. I wouldn’t go more than a year, regardless of how few miles you put on the car.

Get the oil changed at a mechanic who specializes in your type of car (which may even be the dealer). Use the oil change as a sort of job interview for when you may need more costly repairs or maintenance. Was the shop pleasant to work with? Did they do a good job? Did they try to sell you stuff you don’t need? Or the opposite, recommend other services called for by the manufacturer at your mileage, or catch a true problem you’d been unaware of?

Oil changes, and other maintenance can be expensive, but part of owning some cars. If you don’t like doing it, for your next car get one that doesn’t need oil changes.

17

I venture the guess, should a law come out that obliges the car-maker/seller to take care of oil-changes for free for the first 100.000km, the service intervalls they call for would be different from the ones they stipulate today. So there is a huge “commercial / non-technical” component in that recommendation.

Today, Subaru has an intrinsic motivation to call for frequent oil change b/c:

a.) they dont have to pay for it (you do) … and the higher, they set the frequency, the more often cars will come back into their dealerships, which will gladly find $hit to upsell you, like the $9 pollen-filter for $99.

b.) the cars engine will live longer with fresher oil *), but that is also true for 1000mile intervalls (so technically 1000 miles oil changes are “better” than 3k miles intervalls than 5k intervalls … so its a continuum rather than a anything else, and they chose to position themselves.)

c.) setting an absurdly low treshold will help them probably shed cheaply a certain percentage of warrenty claims due to it (you exceeded the limit of oil-changes between 24.000k miles and 27.000km - this is the reason your motor exploded now, 3 years later at 99.000miles)

and wouldnt you know it, Subaru Chile’s recommendation is - change oil every 15.000km, thats what, 9k miles - triple of what’s called for in .ca!!! - so yeah … they are milking you - b/c they can get away with it

(a rather good google translate)
Oil and filter change frequency
To keep your Subaru in perfect condition, it is recommended that you change the oil and filter every 15,000 kilometres, and 10,000 kilometres for the Evoltis model. However, this frequency may vary depending on the car model and conditions of use. For example, if you drive in extreme conditions such as dusty roads or frequent short journeys, it may be necessary to do it more often.

*) with higher oil-change frequency, increases the risk of a mechanic screwing up and ruining the threads in the soft aluminum block or some other misfortune

18

Well, my Honda is the first car I ever owned that came with pure synthetic as part of its factory presentation. I have maintained oil changes with pure synthetic ever since and, even though I commute 40 high speed interstate miles per day, I only get about two oil changes a year. I have an “oil life” gauge, and it triggers at 15% oil life. Everything has been fine.

19

My 2019 Colorado has a v6 & 2025 xt5 that I change every 6 months or 4000 miles which ever comes first ! The manufacturer recommends 7000? Which I choose to disregard. I only put an average 5 to 7 thousand miles a year on each of my vehicles so it’s a small expense to keep there oil clean. I will add that I do the oil changes myself which saves me a few dollar and gives a chances to look for leaks and know that filters were changed and everything was tightened correctly!

20

I use syntethic on my 2014 Mazda 3 (and previously 2004 Mazda 3 – hey, that means I’m due for a new pre-owned Mazda!) and I’ve changed every 7500-10,000 miles. I believe that’s what’s written in the manual (every 7500 or annually). I don’t follow the “every 3000 miles” the oil changes places say. At any rate, I try to change annually, sometimes 18 months will go by without a change. (And I’ve probably pushed 12.5K, maybe even 15K miles at some point.) I’ve never had any sort of issue, and neither of my Mazdas have ever needed engine work (or really anything beyond maintenance like changing brakes and rotors) nor showed any signs of wear or reduced mileage or anything. The first one ran 150K miles before I sold it, and the current one is much more lightly used (due to another car in the family) at 80K miles.