2017 Subaru 2.5L Interval Question

HowAboutThis

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Ours runs pretty high oil temps in the 104C range on easy hwy driving in the summer, so I don’t really like to push the OCI to much further. I’m also running 5w30.
You have a Forester of 2017 or similar variety? I should've brought my OBD scanner and checked the temps! Would've been interesting. Thanks for the info.
 

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Ours runs pretty high oil temps in the 104C range on easy hwy driving in the summer, so I don’t really like to push the OCI to much further. I’m also running 5w30.
Interesting, I tend not to think of that as pretty high, that's what the truck was running yesterday spinning 2K going down the highway. I see higher than that in the Jeep:
DAC2BA80-F0F2-4B97-B59C-335FD9E03AB7_1_105_c.jpeg


Does this vehicle have a coolant/oil heat exchanger? If so, I expect that temp is "normal" based on what I see with ours that do.
 
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You have a Forester of 2017 or similar variety? I should've brought my OBD scanner and checked the temps! Would've been interesting. Thanks for the info.
You can monitor oil temps in the triple gauge screen of the information screen. I've momentarily hit 255 F on my 18 forester 6mt. Usually highway stays around 210-235. Mine does not consume much oil but I do notice the consumption rate increase during sustained light load highway driving at higher rpm. Higher load driving at lower rpm it does not consume. I monitor calculated load to better mimic the automatic with my manual gear changes and throttle input and so far does not consume excessively at all.
 

HowAboutThis

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You can monitor oil temps in the triple gauge screen of the information screen. I've momentarily hit 255 F on my 18 forester 6mt. Usually highway stays around 210-235. Mine does not consume much oil but I do notice the consumption rate increase during sustained light load highway driving at higher rpm. Higher load driving at lower rpm it does not consume. I monitor calculated load to better mimic the automatic with my manual gear changes and throttle input and so far does not consume excessively at all.
Wait, what? How do I get that screen? I either don't have that option or I'm ignorant. Time for a Google...
 
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Interesting, I tend not to think of that as pretty high, that's what the truck was running yesterday spinning 2K going down the highway. I see higher than that in the Jeep:
View attachment 109483

Does this vehicle have a coolant/oil heat exchanger? If so, I expect that temp is "normal" based on what I see with ours that do.
No, it doesn't have a coolant/oil exchanger, the 3.6 did. It has active front shutters, which sort of allow the engine block more cooling I guess, and its a "remote" filter placed up beside the engine with some extra tubing which helps cool I guess.
Out or curiosity, earlier this year in 24C air temps, I just ran the engine at 3500-4000 rpm for a few miles and was hard on the throttle up some hills, just to see that the oil temp would get to, and it only got to 110C? So unless I'm towing a box trailer or something that catches the wind, up a mountain pass, it doesn't seem to need a cooler? I just find it odd that the oil temp gets that high at 1500rpm with little load, and but then rev'd at 4k, for a few minutes, it only goes up a bit? I guess its not a problem anyways.
 
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Just saw page 3-72 in the owner's manual. I'll be darned. I'd been through that menu a few times but never knew I could add in oil temps!!! Future fun!
Also throttle percentage, which I use more when I have time to go for some extra mpg's... The CVT is pretty magical for holding high instantaneous mpg's while climbing a small hill with a fixed throttle percentage. Some hills you get over just losing 5-6mph while maintaining over 30mpg, and then go back to 45+mpg on the flat after the hill at normal speed.
 
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No, it doesn't have a coolant/oil exchanger, the 3.6 did. It has active front shutters, which sort of allow the engine block more cooling I guess, and its a "remote" filter placed up beside the engine with some extra tubing which helps cool I guess.
Out or curiosity, earlier this year in 24C air temps, I just ran the engine at 3500-4000 rpm for a few miles and was hard on the throttle up some hills, just to see that the oil temp would get to, and it only got to 110C? So unless I'm towing a box trailer or something that catches the wind, up a mountain pass, it doesn't seem to need a cooler? I just find it odd that the oil temp gets that high at 1500rpm with little load, and but then rev'd at 4k, for a few minutes, it only goes up a bit? I guess its not a problem anyways.
The 2017 US model forester does not have grill shutters. What year is yours?
 
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@HowAboutThis I have a 2018 Legacy with the same engine as you. I also have a 2019 Impreza. Both are Sports but that doesn't matter. Since I am under warranty I have been doing the 6k/6Month change. Since I have my wife drive the Legacy a few days a week that actually works out for me with both 6k and 6 months being the same. Most of her miles are highway but getting to the highway is ~6 - 10 miles. Her round trip miles are ~80. So I follow the Subaru recommended mileage. Prior to my wife driving the car, I was doing maybe 2000 - 2500 mile oil changes. Car has 38k now. In my Impreza it's not even close. Sometimes I'm lucky to get maybe 2k miles after 6 months sometimes less. Right now I'm at ~1500 and am due for a change this month. I may push it out to next month since I am going down to Wildwood which is ~350 miles around trip plus I have a few gigs that will put maybe a few extra hundred miles on it. It'll end up being about 7 months but still less than 2500 miles. For peace of mind and warranty I just do it. Car has 13,500 miles on it. Since both cars have the 100k/10yr warranty I don't want to give them an excuse to void any type of work.

Please understand that this is what I do and is my own opinion. It pains me to change the Impreza so often but the $25 (after oil rebates and buying filters in bulk) it costs me twice a year isn't killing the wallet. In fact, I have 3 cars that I change twice a year. The other is a CR-V. It's nice cause it uses the same oil but I have to keep some different filters around.
 
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None of this road trip is considered severe service unless you are hauling/towing. Even with the 2 quarts of fresh oil added, I would stick with your normal 6k mile interval, just for simplicity.
 
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No, it doesn't have a coolant/oil exchanger, the 3.6 did. It has active front shutters, which sort of allow the engine block more cooling I guess, and its a "remote" filter placed up beside the engine with some extra tubing which helps cool I guess.
Out or curiosity, earlier this year in 24C air temps, I just ran the engine at 3500-4000 rpm for a few miles and was hard on the throttle up some hills, just to see that the oil temp would get to, and it only got to 110C? So unless I'm towing a box trailer or something that catches the wind, up a mountain pass, it doesn't seem to need a cooler? I just find it odd that the oil temp gets that high at 1500rpm with little load, and but then rev'd at 4k, for a few minutes, it only goes up a bit? I guess its not a problem anyways.
IIRC, there were a few long threads on subaruforester.org
I only counted two marginal successes in cutting down the oil consumption in reading many pages of those threads.
1. A person added an additional oil cooler. You should be able to fit an OEM one atop the oil filter mount (21311's). This roughly halved the person's consumption.
2. A person started using mobil 1 0w-40. This halved the person's consumption.

My oil consumption was pretty abysmal, but I halved it by going up viscosity. Cold start is a non-issue where I live in Texas.
At my old job and commute, I would consume 1.5qt in 4000 miles. Would drive 70 miles to work, 90% of which was 70mph, ~2.9k rpm. I could tell at that time that the consumption seemed pretty tied to engine speed. Back then if I really wanted to prove that it would chug the oil, I could've just driven to work a few times in 4th gear (I have a 6MT) and the stick would be dry for sure before the end of the week on 0w-20. But I don't trust that getting the short block replaced solves the root problem anyway. Not after all that reading.

I'm not sure what to make of it, but they have changed PCV P/N multiple times in the FB25's life. I have never pulled my PCV hose off and it not be oily on the inide, even after replacing the PCV. I figured the internal baffling and/or blow-by + PCV design is at least a little suspect IMO. Especially after I put on an oil catch can (not typical decision for a port-injected vehicle..) and it would fill up every 100 op hours. It doesn't nearly fill 2 oz in an OCI now. I figured it was being force-fed it's own oil through the PCV when it got heat soaked, which makes top-ring coking worse, which makes blow-by worse, which could explain why the 6MT owners get the shaft earlier since they highway cruise at higher rpms than the CVT folk.

Since the start of my new job, my car rarely operates for longer than an hour, and the commute is 30minutes at 60 mph. Consumption rate is less at the moment. Looking longingly at HPL's consumption performance on the FB25.
 
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The 2017 US model forester does not have grill shutters. What year is yours?
My Outback in my signature does, identical motor I believe to your forester. The 2018 Outback had some revisions to the CVT compared to the 2017 Outback, and added the grill shutters. The 2017 Outback drivetrain was identical to the 2017 Forester except the addition of a CVT cooler and have slightly higher ratio differentials presumably for the extra tow rating.

We don't seem to have a significant consumption issue in our 6k mile intervals, but the motor spends most of its time at 1600rpm going down the highway.
 
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IIRC, there were a few long threads on subaruforester.org
I only counted two marginal successes in cutting down the oil consumption in reading many pages of those threads.
1. A person added an additional oil cooler. You should be able to fit an OEM one atop the oil filter mount (21311's). This roughly halved the person's consumption.
2. A person started using mobil 1 0w-40. This halved the person's consumption.

My oil consumption was pretty abysmal, but I halved it by going up viscosity. Cold start is a non-issue where I live in Texas.
At my old job and commute, I would consume 1.5qt in 4000 miles. Would drive 70 miles to work, 90% of which was 70mph, ~2.9k rpm. I could tell at that time that the consumption seemed pretty tied to engine speed. Back then if I really wanted to prove that it would chug the oil, I could've just driven to work a few times in 4th gear (I have a 6MT) and the stick would be dry for sure before the end of the week on 0w-20. But I don't trust that getting the short block replaced solves the root problem anyway. Not after all that reading.

I'm not sure what to make of it, but they have changed PCV P/N multiple times in the FB25's life. I have never pulled my PCV hose off and it not be oily on the inide, even after replacing the PCV. I figured the internal baffling and/or blow-by + PCV design is at least a little suspect IMO. Especially after I put on an oil catch can (not typical decision for a port-injected vehicle..) and it would fill up every 100 op hours. It doesn't nearly fill 2 oz in an OCI now. I figured it was being force-fed it's own oil through the PCV when it got heat soaked, which makes top-ring coking worse, which makes blow-by worse, which could explain why the 6MT owners get the shaft earlier since they highway cruise at higher rpms than the CVT folk.

Since the start of my new job, my car rarely operates for longer than an hour, and the commute is 30minutes at 60 mph. Consumption rate is less at the moment. Looking longingly at HPL's consumption performance on the FB25.
Brian553 I have obsessed over the consumption issue like you with FB and EJ and I believe prolonged low load operation plays a significant part. I believe this results in piston rings that are not exercised the same as one may expect. I have no proof but have observed most oil consumption FB and EJ engines to be the ones that see prolonged low load use, as well as less piston slap. The ones with (mild) piston slap (and more movement of the piston rings as a result) and or proper load consume very low amounts from what I can gather.

Most manual drivers keep engine load lower than the cvt does. Sure they may floor the car periodically and see 85-100 percent load briefly, but this is what the cvt does almost every time you try to build any momentum at all, even at low rpms. To do this in my manual transmission FB25 you have to give the accelerator pedal quite a bit of travel, I believe more than most drivers would find comfortable to do every day. Most manual drivers are comfortable cruising at higher rpms and maybe 15-20 percent cruising load at lower vehicle speeds. Imagine the volume of air sealed in the combustion chamber with these different types of regular use and how that turns out for long term ring cleanliness and oil consumption. I too use thicker oil than printed on the oil cap, use higher load regularly in my FB and have low consumption. I look forward to your results with HPL. I will post uoa's from my high mileage EJ (420k mi) and lower mileage 73k fb25 when I have more reports and is appropriate. I believe the OPs oil consumption at high speeds occurs during high speed light loads. Yes fighting the wind and driving 80+ is high load, but usually not continuously over 1,000 miles. There are times where 80 mph and higher rpm involves light load such as slight downhill etc.
 
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Brian553 I have obsessed over the consumption issue like you with FB and EJ and I believe prolonged low load operation plays a significant part. I believe this results in piston rings that are not exercised the same as one may expect. I have no proof but have observed most oil consumption FB and EJ engines to be the ones that see prolonged low load use, as well as less piston slap. The ones with (mild) piston slap (and more movement of the piston rings as a result) and or proper load consume very low amounts from what I can gather.

Most manual drivers keep engine load lower than the cvt does. Sure they may floor the car periodically and see 85-100 percent load briefly, but this is what the cvt does almost every time you try to build any momentum at all, even at low rpms. To do this in my manual transmission FB25 you have to give the accelerator pedal quite a bit of travel, I believe more than most drivers would find comfortable to do every day. Most manual drivers are comfortable cruising at higher rpms and maybe 15-20 percent cruising load at lower vehicle speeds. Imagine the volume of air sealed in the combustion chamber with these different types of regular use and how that turns out for long term ring cleanliness and oil consumption. I too use thicker oil than printed on the oil cap, use higher load regularly in my FB and have low consumption. I look forward to your results with HPL. I will post uoa's from my high mileage EJ (420k mi) and lower mileage 73k fb25 when I have more reports and is appropriate. I believe the OPs oil consumption at high speeds occurs during high speed light loads. Yes fighting the wind and driving 80+ is high load, but usually not continuously over 1,000 miles. There are times where 80 mph and higher rpm involves light load such as slight downhill etc.
If the load goes up, the rings are being forced to move more, encouraging them to proud and rotate (good). If there is piston slap, the cylinder walls may score from the piston skirt in the direction of piston travel, which channels oil that can't be scraped by the rings (bad, goes to combustion chamber). The pistons are more likely to start to slap if the rings stick. If the oil heats up hotter than the designer intended/expected (which can be encouraged with prolonged high load use), the active viscosity will follow by dropping (oil temp control). Varnish/deposit control of the rings is determined by the specced capabilities of the oil, and its time in-use (API rating, ACEA spec, ect.) I'm not sure that I have tracked those that do high load vs low load regularly (especially between CVT vs MT owners), but the above applies nonetheless. If the person has been doing periodic high load since the beginning (assuming good break-in) when there is minimal blowby, then he is helping stabilize low blowby "mechanically" at the rings. If a person is not stressing out the deposit prevention capabilities of their choice oil (my PO was not that case,) then they're helping stabilize low blowby "chemically" at the rings. If the blowby is so high that the PCV cannot keep up, then the crankcase pressure increases and the oil is pushed out against the rings towards the combustion chamber.

My case has been that high load did not free my rings, and my consumption followed high load, not low load (I tried those tests ~8 months ago.) I am going the "chemical route," and accept that either they are unfree-able, overworn, or my cylinder walls are very scored, or a mixed combo. I have not had any detectable consumption this OCI, and I am ~68 hours in. Being my commuter, I definitely don't like cruising at high rpm, in fact I wish the 6th gear was taller and I could cruise 70mph at 2k rpm... oh well, wah-wah. I believe most 6MT don't like it either for the same reason, do you?
 
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If the load goes up, the rings are being forced to move more, encouraging them to proud and rotate (good). If there is piston slap, the cylinder walls may score from the piston skirt in the direction of piston travel, which channels oil that can't be scraped by the rings (bad, goes to combustion chamber). The pistons are more likely to start to slap if the rings stick. If the oil heats up hotter than the designer intended/expected (which can be encouraged with prolonged high load use), the active viscosity will follow by dropping (oil temp control). Varnish/deposit control of the rings is determined by the specced capabilities of the oil, and its time in-use (API rating, ACEA spec, ect.) I'm not sure that I have tracked those that do high load vs low load regularly (especially between CVT vs MT owners), but the above applies nonetheless. If the person has been doing periodic high load since the beginning (assuming good break-in) when there is minimal blowby, then he is helping stabilize low blowby "mechanically" at the rings. If a person is not stressing out the deposit prevention capabilities of their choice oil (my PO was not that case,) then they're helping stabilize low blowby "chemically" at the rings. If the blowby is so high that the PCV cannot keep up, then the crankcase pressure increases and the oil is pushed out against the rings towards the combustion chamber.

My case has been that high load did not free my rings, and my consumption followed high load, not low load (I tried those tests ~8 months ago.) I am going the "chemical route," and accept that either they are unfree-able, overworn, or my cylinder walls are very scored, or a mixed combo. I have not had any detectable consumption this OCI, and I am ~68 hours in. Being my commuter, I definitely don't like cruising at high rpm, in fact I wish the 6th gear was taller and I could cruise 70mph at 2k rpm... oh well, wah-wah. I believe most 6MT don't like it either for the same reason, do you?
Yes. I believe that regular high load before consumption begins keeps consumption from starting but once it starts its difficult to turn around. While high load results in high heat and potentially deposits I believe this high load is necessary in these engines. This is most apparent in manual versus cvt. Sure, someone may believe their engine is hardly working hard while turning 1600 rpms up a rolling hill but in reality calculated load may be holding 80-90 percent. I'm fortunate to take care of many FB engines and EJ engines and regular high load is the consistent factor in each instance I've noticed yet is unmentioned anywhere. I've had the best results running euro spec oils (m1 0w40, 0w30 esp) and periodic engine flushes (liqui moly lm2037) say once every 3 or 4 oil changes. I dont believe oil alone is enough to keep the rings clean over the long run. Although HPL looks promising with other engine examples observing less oil use and good cleaning. At some point I would love to try HPL in mine. I agree with you on the 6mt cruising rpm, this is also the only time mine experiences (very slight) consumption, like the OPs excessive consumption but otherwise minimal in normal use.
 
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Couldn't they have prescribed the installation of different rings (ones that rotated more in the typical cruising loads) in the warranty correction that went out? I've never heard of low load causing this issue in any other vehicle.
 
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Couldn't they have prescribed the installation of different rings (ones that rotated more in the typical cruising loads) in the warranty correction that went out? I've never heard of low load causing this issue in any other vehicle.
I've wondered if the secondary balance of the boxer plays a role in this as well. I know that diesels that aren't loaded properly such as a generator that is oversized for its application or only used for 20 minute weekly exercise without full load use can become an oil burner.
 
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Car is usually driven 55-65mph to commute. No major hills, wind, etc. I'd consider it a super easy on oil commute. And often push past the 6k change interval.

Recently road tripped about 2k miles each way. Uphill, downhill, mountains, into strong Midwest winds, all with cruise set at 80+mph at times. Is this severe? I added 2 quarts of oil, I'm assuming due to the engine load and higher than typical rpms (4k+ uphill).

Would you change at 6k or let it go until 7-7.5k?

Looking forward to contradicting views already!
I have owned many subarus and about to get another. Starting way back with a 1990 Loyale thru many Impreza Wagons, a Justy, an SVX(!), various Foresters and now a base Outback.

The EJ and the FB 2.5 use oil and I think for different and varied reasons - some of them improperly drilled valve guide pilot holes(TSB), some ring and piston design(TSB) , and many just a healthy PCV scavenging on a crankcase design that puts the crank and rod bearing spillage close to the vacuum side of the PCV.

I would hazard a guess your usage is just PCV related - unless you have been seeing excessive consumption in regular commuting prior to these trips. The PCV are usually clean as a whistle if you regularly change your oil - so no use changing it.


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SVX.jpg


- 1987 Subaru Justy Brochure cover courtesy of Import Archive
 
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