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More Frequent Oil Changes & Severe Service (Maintenance Interval Suggestions)

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I am slowly creeping up towards my 30,000 mile service. From previous history and driving habits, I have elected to increase the frequency of my oil changes. I'm curious if anyone else has done the same or is already doing the same.

The main reason for increasing my oil change interval to 4,000 miles instead of the suggested 6,000 normal service is because of the turbocharger itself and the suburban driving. I remember that years ago - with the Gen3 Outback XT's - Subaru had made a blanket statement that all "turbos" are considered severe service, no matter what. Now, the history here is that this was likely related to the discovery of oil starvation and the clogged banjo bolts with the previous intervals.

I formerly owned a 2009 Legacy (2.5 EJ253) and I believe the oil change interval at the time was either 3,750 for severe or 7,500 for normal driving. Being in a suburb outside of New York City, I elected to perform the oil change intervals "around the 3,750" mark, and in practice, this was somewhere closer to the 4,000 mile mark. There were one or two instances of when "we" (the Mrs. is the primary driver of the Legacy) exceeded the 4,500 to 5,000 mile mark, that I had noticed the oil consumption increase. This was still in the head gasket era, so I truly don't know if it was a head gasket problem, coolant problem, combination of the two, or just general oil consumption due to the commute. For reference, her commute still does take her through the morning rush, which is not pleasant and pretty much summarizes the severe service interval: less than 10 miles each way, stop-and-go, lots of urban driving traffic.

My driving, however, has changed as I've modified my route to include toll highways. It is reliably about the same amount of time unless there's a major accident: about 20 miles each way, nearly all highway at 55 to 65 mph, and generally not aggressive. I previously had also been taking a more urban route that would take me longer, but would be half the mileage (and those miles were "very urban" - traffic signals every couple hundred yards to force people to slow down.)

So, every day my temperature comes up to full speed and runs there for about 10-15 minutes of the typical 25 minute commute. Once I'm on the highway I will let adaptive cruise control take over for me.

I am planning to:
  • Continue oil changes around the 4,000 to 4,500 mark, depending on convenience and availability to have the maintenance done
  • Have the front and rear differential fluid changed every 30,000 miles
  • Continue having tire rotations performed at every other oil change service (8,000 to 9,000 miles)
  • Change my Cabin Air and Engine Air filters myself yearly, regardless of mileage (typically around now - once the leaves have fallen and there's less dust)
  • Spark Plugs changed at suggested 60,000 mile interval
  • Brake Fluid changed at 30,000 mile intervals
I am considering:
  • Having the CVTF changed at the 60,000 mile service
  • Having the Coolant changed at the 60,000 mile service
  • Changing the battery at the 5 year mark unless needed earlier (likely a Costco available replacement)
  • Changing my OEM tires to Falken Wildpeaks at the 60,000 mile service unless needed earlier
  • Changing the PCV valve at 60,000 mile service
Anything else you'd suggest? I believe that the fuel injector services and things like that are largely unnecessary for proactive/preventative service, but if I had issues, I would not hesitate to do it. Aside from the CVTF, the only thing that I am curious about, maintenance wise, is the direct injection system. It does seem like these carbon buildup issues aren't happening - at least not yet. The Mrs. drives a Honda with a DI engine as well, and that one seems normal as we pass 60,000 miles and counting.

At this point, with 4,000ish mile oil change intervals, I have not noticed any measurable oil consumption, and I am hoping to keep it that way. While I admit that the interval is probably slightly "over the top" for the highway driving I am now doing (started the new route earlier this year), it seems like proverb of "oil is cheap, engines are not" is ringing true.

If you fall into the severe or accelerated intervals mentioned above in the poll, would you mind posting below on why you've chosen to do that? Thanks!

What maintenance intervals are you following?

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2020 Onyx
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I'm on time intervals not mile intervals. Oil change every 6 months (2000 miles of city stop and go driving). According to Subaru, if I strictly followed severe service intervals it would be every 3 months (1000 miles) and that just seems excessive to me.
 

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2018 Outback Premium 2.5 w/ Eyesight
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edit- realize this is gen6 forum, still sharing fwiw…5000 miles. It’s easy to remember and while I realize it’s not exactly splitting the difference between normal and severe it’s gone well for my 2014 Legacy and 2018 Outback, no noticeable oil consumption in either car. Works out to about every 6-7 months in legacy and every 4-5 in outback. Our usual mix of driving is rural roads and highway, actually pretty close to 50/50 I’d say. We don’t drive particularly aggressively.

5000 was also our dealer’s recommendation when we bought both cars there. It’s still what they put on reminder sticker. I’ve seen no reason to change from that as of yet, whether my independent shop or dealer does the service—that depends on convenience and my schedule.
 

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2022 Outback Wilderness
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Seems like you have a good approach here. I don’t do a lot of city driving and don’t have a regular work commute, but I do drive quite a bit on weekends and usually once a week or so on a longer drive. So I end up doing about 6,000 miles every 4 months or so, with almost 90% of that as rural/highway driving. That’s why I do my oil changes every 6,000 miles and go by miles rather than time since I drive a bit more than normal - but I do check the dipstick regularly.

On everything else, the mileage interval you posted for all the key items seems sensible and something I’ll follow too. Only exception being the CVT - I plan to do my first fluid change at around 24k miles (which will be sometime next spring), and thereafter about every 40k miles or so. Depending on how the fluid looks at the first service, I may or may not decide to shorten the interval after that. But the CVT is the only thing I am willing to follow the severe service schedule if needed. On oil changes and the other stuff, I know that with my use case (from prior experience), I should be fine with regular intervals.
 

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I just stick with the 6000 mile changes. I live at least somewhat near you based on your description of NYC suburbs. My commute (3-4 days a week) is down 684. As I expect you know that can mean either stop and go traffic, or 80mph depending on the day. I've only an XT for a bit over a week, but we follow the same practice with our Ascent (same engine)

FWIW my dealer still recommends 6k/6mo oil changes.
 

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I am slowly creeping up towards my 30,000 mile service. From previous history and driving habits, I have elected to increase the frequency of my oil changes. I'm curious if anyone else has done the same or is already doing the same.

The main reason for increasing my oil change interval to 4,000 miles instead of the suggested 6,000 normal service is because of the turbocharger itself and the suburban driving. I remember that years ago - with the Gen3 Outback XT's - Subaru had made a blanket statement that all "turbos" are considered severe service, no matter what. Now, the history here is that this was likely related to the discovery of oil starvation and the clogged banjo bolts with the previous intervals.

I formerly owned a 2009 Legacy (2.5 EJ253) and I believe the oil change interval at the time was either 3,750 for severe or 7,500 for normal driving. Being in a suburb outside of New York City, I elected to perform the oil change intervals "around the 3,750" mark, and in practice, this was somewhere closer to the 4,000 mile mark. There were one or two instances of when "we" (the Mrs. is the primary driver of the Legacy) exceeded the 4,500 to 5,000 mile mark, that I had noticed the oil consumption increase. This was still in the head gasket era, so I truly don't know if it was a head gasket problem, coolant problem, combination of the two, or just general oil consumption due to the commute. For reference, her commute still does take her through the morning rush, which is not pleasant and pretty much summarizes the severe service interval: less than 10 miles each way, stop-and-go, lots of urban driving traffic.

My driving, however, has changed as I've modified my route to include toll highways. It is reliably about the same amount of time unless there's a major accident: about 20 miles each way, nearly all highway at 55 to 65 mph, and generally not aggressive. I previously had also been taking a more urban route that would take me longer, but would be half the mileage (and those miles were "very urban" - traffic signals every couple hundred yards to force people to slow down.)

So, every day my temperature comes up to full speed and runs there for about 10-15 minutes of the typical 25 minute commute. Once I'm on the highway I will let adaptive cruise control take over for me.

I am planning to:
  • Continue oil changes around the 4,000 to 4,500 mark, depending on convenience and availability to have the maintenance done
  • Have the front and rear differential fluid changed every 30,000 miles
  • Continue having tire rotations performed at every other oil change service (8,000 to 9,000 miles)
  • Change my Cabin Air and Engine Air filters myself yearly, regardless of mileage (typically around now - once the leaves have fallen and there's less dust)
  • Spark Plugs changed at suggested 60,000 mile interval
  • Brake Fluid changed at 30,000 mile intervals
I am considering:
  • Having the CVTF changed at the 60,000 mile service
  • Having the Coolant changed at the 60,000 mile service
  • Changing the battery at the 5 year mark unless needed earlier (likely a Costco available replacement)
  • Changing my OEM tires to Falken Wildpeaks at the 60,000 mile service unless needed earlier
  • Changing the PCV valve at 60,000 mile service
Anything else you'd suggest? I believe that the fuel injector services and things like that are largely unnecessary for proactive/preventative service, but if I had issues, I would not hesitate to do it. Aside from the CVTF, the only thing that I am curious about, maintenance wise, is the direct injection system. It does seem like these carbon buildup issues aren'
 

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PilotXT,
That is the best maintenance schedule I have ever seen!!!
I would definitely look at an oil cannery separator with a DI sub. I have on a 2016 with port injection and feel it is worthwhile even without di.
 

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2022 Outback Touring
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Seems like you have a good approach here. I don’t do a lot of city driving and don’t have a regular work commute, but I do drive quite a bit on weekends and usually once a week or so on a longer drive. So I end up doing about 6,000 miles every 4 months or so, with almost 90% of that as rural/highway driving. That’s why I do my oil changes every 6,000 miles and go by miles rather than time since I drive a bit more than normal - but I do check the dipstick regularly.

On everything else, the mileage interval you posted for all the key items seems sensible and something I’ll follow too. Only exception being the CVT - I plan to do my first fluid change at around 24k miles (which will be sometime next spring), and thereafter about every 40k miles or so. Depending on how the fluid looks at the first service, I may or may not decide to shorten the interval after that. But the CVT is the only thing I am willing to follow the severe service schedule if needed. On oil changes and the other stuff, I know that with my use case (from prior experience), I should be fine with regular intervals.
Are you considering a complete fluid change out or simply a drain and refill?
 

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2015 3.6R Limited w/ES
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Curious why you'd want to change the coolant at a 60k mile interval. This is P-HOAT long-life coolant with decades of proven performance at well beyond Subaru's recommended interval (not sure if it changed, but it's 220k km for Gen 5s). IMO, there's simply no reason to change it early unless the cooling system requires servicing or it gets contaminated.

Also, just FYI and FWIW, Subaru has stated that it's normal for the CVT fluid to darken considerably with use and that the visual appearance is not a reliable indicator of fluid condition unless it's obviously contaminated with something like water or metal. From the UOAs, and everything else I've read around here, it seems 60k is a prudent interval unless you tow or drive extremely aggressively.
 

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'20 Outback Onyx XT AGM/'04 Forester XT
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Even after turbo failure in my FXT, probably caused by ignoring the short intervals mandated by SoA as you mentioned, I stuck with 5,000 mile intervals and put another ~110k miles on it before I sold it. I also even kept in all of the banjo bolt screens at the recommendation of the lead senior master tech at my dealer.

For the Outback, even though it's a turbo with excessive fuel dilution being common I'm sticking with 5,000 mile intervals. Since the FA24DIT was out for a year before it was put into the Outback, I believe that we would have heard about failures by now if there was an issue ( I recall one on an Ascent). I'm not even worried about slightly exceeding 5,000 mile intervals on occasion. I would expect that a lot of people go with 6k mile intervals anyway.
 

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2022 2.4L Touring XT (Ordered 26FEB22)
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I'm at 6,000 mile intervals now . . .even though the oil folks are indicating 25,000 would be fine. My greatest indicator is the analysis after each oil change. At one time, Porsche recommended 20,000 and I think the Corvette was 10,000. There are so many of us who grew up in the "3,000 miles between oil changes" that it's a whole new world.

Rectangle Organism Font Circle Screenshot


Ordinarily . . . I'd laugh this stuff off. But, I spent a couple years on development of a new motor with Rotax in Austria that involved finding the best oils for the street version and for our World Superbike version. Part of the testing involved filling the motor with oil, running it for 30 minutes to bring everything up to temperature, shutting it down, draining the oil, restarting the motor and pinning it at redline for a couple hours.

The current crop of oils (we found 2 that excelled) is amazing. This was true "don't try this at home" stuff . . . but, it was interesting.

It's pretty tough in this day and age to buy a "bad" oil. There was a time, in the days of cardboard cans . . when there were some really substandard stuff. If you are putting current grade quality oil in your car, oil failures have become pretty darn unlikely. The last car I kept to over 100,000 got an amazing report from Blackstone at 108,000 showing no residual metals or signs of wear.

But, for now . . . I'm sticking with 6,000 mile intervals for several reasons.

Fun video from one of the first times we took the new bike (Eslick #69) racing . . . easy to see how we got named "Best Handling Motorcycle". :)

 

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2022 Onyx XT
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I'm at 6,000 mile intervals now . . .even though the oil folks are indicating 15,000 would be fine. My greatest indicator is the analysis after each oil change. At one time, Porsche recommended 20,000 and I think the Corvette was 10,000. There are so many of us who grew up in the "3,000 miles between oil changes" that it's a whole new world.
Blackstone suggested I could run 7k but I think I'll stay in the 5ish range for peace of mind.
 

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2020 Onyx
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Generic oil change recommendations don't necessarily take into account the specifics of a particular engine - e.g. turbocharged, direct injection, both of which normally would shorten an interval. Turbochargers for just increased demands on the oil, and direct injection for soot loading of the oil (and extra dilution for short trips). Newer oils are developed generally with those in mind, because of timing chain wear, turbo bearings, since direct injection turbo is pretty common these days. Subaru used to give different oils and schedules for their turbo vs non turbo engines, but now the turbo and naturally aspirated have the same schedule on the same oil. Used oil analysis results show clearly that the turbo motor reduces oil viscosity at around the 3000 mile mark, while the naturally aspirated engine does not.

90% of my trips are less than 5 miles. Severe Service especially for a direct injection engine. As crazy as this sounds, according to Subaru's report, my car's average speed is 18 miles per hour, despite taking freeway trips for the other 10% of my drives - it's slow surface driving both before and after taking the freeway so... ugh.
 

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2022 Outback Wilderness White (the best color)
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I drive my car everyday. Well maybe 360 out of 365 days per year. And I only total about 4800 miles per year. So I follow the 6000 miles or 6 months. So I change the oil at 6 months and less than 3000 miles on it.

Don
 

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Discussion Starter · #18 ·
There are ways to do a complete change - at least I’ve seen it on a Forester on their forums - using a vacuum or intake hose to pull clean stuff through. There is a lot of potential waste fluid doing it this way though, so you need to make sure you have a lot of extra fluid on hand.

I am also not sure what my local department does; technically the maintenance book says only change if you tow, and that is a 24,855 mile interval which is 40,000 kilometers.

Regarding the coolant, my previous experience with my Subarus before this - including my 09 Legacy that had Super Coolant - is that they become more acidic or contaminated over time which in turn will react with the radiator metals itself. I suppose this could be an obsolete mindset, but likely stems from the former coolant solutions creating some type of latent electrical charge (ions?) which also created problems in the Gen3 OB/Gen4 Legacy which were 2009 and earlier.
 

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There are ways to do a complete change - at least I’ve seen it on a Forester on their forums - using a vacuum or intake hose to pull clean stuff through. There is a lot of potential waste fluid doing it this way though, so you need to make sure you have a lot of extra fluid on hand.
If you talking about the CVT then it is a little easier than what a lot of videos try to show. The only purpose of the pump container of extra fluid is to try and put it back in the CVT as it comes out. The CVT is a hydraulic pump already so it doesn't need any vacuum. I have both drained and filled subs and flushed. Most of the how-to videos I have seen use methods of trying to put the fluid back in the transmission as it comes out. The easiest way is to fill it all the way up, run for 10 seconds, turn the engine off, and refill it again. Do it until the fluid coming out starts having the color of the new fluid you are putting in.
 

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Generic oil change recommendations don't necessarily take into account the specifics of a particular engine - e.g. turbocharged, direct injection, both of which normally would shorten an interval. Turbochargers for just increased demands on the oil, and direct injection for soot loading of the oil (and extra dilution for short trips). Newer oils are developed generally with those in mind, because of timing chain wear, turbo bearings, since direct injection turbo is pretty common these days. Subaru used to give different oils and schedules for their turbo vs non turbo engines, but now the turbo and naturally aspirated have the same schedule on the same oil. Used oil analysis results show clearly that the turbo motor reduces oil viscosity at around the 3000 mile mark, while the naturally aspirated engine does not.

90% of my trips are less than 5 miles. Severe Service especially for a direct injection engine. As crazy as this sounds, according to Subaru's report, my car's average speed is 18 miles per hour, despite taking freeway trips for the other 10% of my drives - it's slow surface driving both before and after taking the freeway so... ugh.
That's why I've been doing 5k changes. Most of my driving is longer and I'm not usually romping on the throttle so I don't think I need to switch to the severe schedule.
 
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