2020 Subaru Legacy 2.5L; M1 EP 0w20 21k mile OCI

I’ve also thought about trying Castrol EP 0w20. It meets MB 229.71 and ACEA C5. I can’t remember why I went with the M1 EP over the Castrol EP, maybe Wal-Mart was sold out or stopped carrying it locally. Does anyone have any experience comparing the two?
 
I’ve also thought about trying Castrol EP 0w20. It meets MB 229.71 and ACEA C5. I can’t remember why I went with the M1 EP over the Castrol EP, maybe Wal-Mart was sold out or stopped carrying it locally. Does anyone have any experience comparing the two?
The new EDGE looks very promising.
 
The results are about 99% contradictory to almost all Subaru DI results by a large margin even with 30 weight oils.

I would say that I drive my car harder than 99% of Subaru owners which I really think is easier on the car.

I also highly doubt that I ever have issues with fuel dilution.
 
I would say that I drive my car harder than 99% of Subaru owners which I really think is easier on the car.

I also highly doubt that I ever have issues with fuel dilution.
So what all highway driving?
I can't even hit 7,500 miles, the recommended oci without running into 4 to 5% fuel dilution.
For example today my wife's car has 2,700 miles on the oil change and I can already smell fuel in the oil so it's probably about 2%. I'm going to run it about 80mph each way, only about 15 miles at that speed to try and burn off some of that fuel.
 
I don’t drive camped in the passing lane holding up traffic like I see most Subarus. The pedal is to the floor on a regular basis. I don’t brake on off ramps when there is no need to. I maintain my speed. I just replaced my factory set of brakes with around 141,000 miles on the car. I get up to speed on the on ramp. I don’t merge with 80 mph traffic going 55 mph. I’m a former state trooper and drive like one. I always use my turn signal, maybe that’s the key. If I’m in the passing lane, I’m passing. I’m a very active driver scanning ahead.

Good luck on your 15 miles at 80 mph. I hear that and feel like you made my point.

When I get to work, I think maybe I should let the car cool for a minute feeling like I just tracked the car. Then other times when I’m not in a rush, I turn the cruise on and drive home like a grandpa getting passed by everyone.
 
I think another thing to keep in mind is how quick I get to 20,000 miles. I’m trying to push my OCI because I was tired of changing my oil all the time. I think with most car using modern oils, you can pretty easily hit 10,000 mile OCIs. In my head, I wouldn’t do anything less, except for the first couple of changes on a new car. If you rarely drive or it takes you a year to get 5,000 miles, I could see fuel dilution and other things being issues, but that’s not my world.

I haven’t been very active on this site for years. I post my UOAs because it’s exciting to some and gives others that data, but the 3,000-5,000 mile OCIs are boring and don’t tell me anything. I feel like people use to try to push and find the limits of oil in the past. I like to see long OCIs and then start splitting hairs to get the lowest wear numbers. I’m also aware my OCD made me a fruity oil nerd, and in my experience, cars can easily run hundreds of thousands of miles without even trying. I’m way more worried about a transmission going out than a failure caused by oil.
 
I think another thing to keep in mind is how quick I get to 20,000 miles. I’m trying to push my OCI because I was tired of changing my oil all the time. I think with most car using modern oils, you can pretty easily hit 10,000 mile OCIs. In my head, I wouldn’t do anything less, except for the first couple of changes on a new car. If you rarely drive or it takes you a year to get 5,000 miles, I could see fuel dilution and other things being issues, but that’s not my world.

I haven’t been very active on this site for years. I post my UOAs because it’s exciting to some and gives others that data, but the 3,000-5,000 mile OCIs are boring and don’t tell me anything. I feel like people use to try to push and find the limits of oil in the past. I like to see long OCIs and then start splitting hairs to get the lowest wear numbers. I’m also aware my OCD made me a fruity oil nerd, and in my experience, cars can easily run hundreds of thousands of miles without even trying. I’m way more worried about a transmission going out than a failure caused by oil.
10k seems pretty doable fershure
 
I think another thing to keep in mind is how quick I get to 20,000 miles. I’m trying to push my OCI because I was tired of changing my oil all the time. I think with most car using modern oils, you can pretty easily hit 10,000 mile OCIs. In my head, I wouldn’t do anything less, except for the first couple of changes on a new car. If you rarely drive or it takes you a year to get 5,000 miles, I could see fuel dilution and other things being issues, but that’s not my world.

I haven’t been very active on this site for years. I post my UOAs because it’s exciting to some and gives others that data, but the 3,000-5,000 mile OCIs are boring and don’t tell me anything. I feel like people use to try to push and find the limits of oil in the past. I like to see long OCIs and then start splitting hairs to get the lowest wear numbers. I’m also aware my OCD made me a fruity oil nerd, and in my experience, cars can easily run hundreds of thousands of miles without even trying. I’m way more worried about a transmission going out than a failure caused by oil.
It would be interesting to see how the CVT fluid is doing, at it sounds like yours does get a work out. My wife drives our Outback pretty hard as well so its always in fake shift mode, where I tend to go for mileage and keep it in the no-shift true CVT mode. I think its quite capable of getting into the high 30's for a tank(which would match the Focus) on 55 roads, but that's up near 600 miles and 2 weeks of my driving so I never get to drive it for a full tank.
 
I think the OP results are excellent. However I just can’t make any sense of it. It’s been repeatedly said here and in other Subaru forums that there’s no difference in dilution with highway or city with FB25DI. Almost everybody has fallen out of grade rapidly by the 2-3k mark on 0w-20. Even I did a Amsoil Signature 0w-20 run and around 4800 miles viscosity was around 7.6. How is that M1 EP is doing 15k-20k miles and not thinned out. Something ain’t right here. Either the engine isn’t DI or the OP just happens to have a real tight engine as far as tolerance stacking goes with his rings/ cylinder. The results are about 99% contradictory to almost all Subaru DI results by a large margin even with 30 weight oils.
Fuel dilution doesn't continually increase over an OCI. It'll be about the same at 20,000 miles as it will be at 2,000 miles.

The reason the viscosity is higher on the 20k mile OCIs compared to the shorter ones is probably oxidative thickening of the oil, which is to be expected at this mileage.
 
I would say that I drive my car harder than 99% of Subaru owners which I really think is easier on the car.

I also highly doubt that I ever have issues with fuel dilution.
I doubt you have such fine control over the D4S system, but still appreciate you sharing the data. Its an interesting discussion.
 
For example today my wife's car has 2,700 miles on the oil change and I can already smell fuel in the oil so it's probably about 2%.
This is similar to Blackstone’s accuracy on fuel testing, but even less accurate.

The sample from my truck (14,400 miles) and Ascent (7300 miles) both smelled identical. The truck was <1%, the Ascent was 6.5%. Both by gas chromatography.
 
It would be interesting to see how the CVT fluid is doing, at it sounds like yours does get a work out. My wife drives our Outback pretty hard as well so its always in fake shift mode, where I tend to go for mileage and keep it in the no-shift true CVT mode. I think its quite capable of getting into the high 30's for a tank(which would match the Focus) on 55 roads, but that's up near 600 miles and 2 weeks of my driving so I never get to drive it for a full tank.
I hate the CVT in this car. It’s my biggest complaint with Subaru’s in general. It’s the reason we bought a Honda Pilot and not the Ascent. My car has always felt jerky and studdery at times under load, long highway hill climbs and at higher speeds. I love the feel of a real transmission now when I drive something without a CVT.
 
I hate the CVT in this car. It’s my biggest complaint with Subaru’s in general. It’s the reason we bought a Honda Pilot and not the Ascent. My car has always felt jerky and studdery at times under load, long highway hill climbs and at higher speeds. I love the feel of a real transmission now when I drive something without a CVT.
Hmm, I wonder what is going on with it? Ours works pretty flawlessly IMO if you drive in normally, but I don't like how it dives the rpms down to 1100rpm in town with 15-20% throttle but other than that it seems to simulate a geared automatic, with quicker smoother shifts than most of those, plus it does match CV the ratios to match power demand pretty nicely at hwy speed if under 20% throttle.
Its far far better than the 5spd AT in our 06 CRV was... That was the most stupidly programmed auto and had the worst manual mode in a auto transmission I've ever used. Was sort of OK unloaded, but with a canoe on the roof, it couldn't hold 5th and then couldn't pick another gear either....
Also I find the CVT much better than the 6spd auto in my Dad's Hemi RAM. The CVT picks the right gear the first time, everytime, at almost any throttle opening, where the RAM holds onto 5th forever, then goes to 2nd or 3rd, revs to the moon, and then goes back to 5th and then 6th.
I prefer manuals, but the sheer efficiency of the CVT is quite impressive if I use gentle throttle inputs. If I'm on the gas hard and then off again, its the same as any geared automatic driven the same way.
 
So about 10oz per 5k miles. Not bad. Have you replaced the PCV recently? It’s understandable with all the highway miles; my EJs never used any oil until I was driving them for at least an hour and a half at 2700+ RPM, which is about 72-75mph with the short-legged 4EATs and 4.111 differentials…
Very good point. Lots of folks simply think (if they even remember them at all) that the PCV is ok and can last forever because they have no timed PCV maintenance minder in the computer/dash/messaging systems. Also nothing in the operator's manual. So human nature is ...forget about it! :rolleyes: Folks do not realize they can get sticky , then operate intermittently. No good. They can even stick open , closed or get plugged. The PCV is such a cheap piece of mind investment , an easy thing to replace that can prevent small issues that can turn into more costly things if ignored.
 
The CVT is smooth and works fine in the city and a lot of times on the interstate, but there is a hill on the interstate on my way home that is a couple of miles long. For whatever reason the car jerks on that hill very frequently. It feels like the drivetrain is a bunch of rubber bands or like the computer is saying we need more power, no, no too much power, back and forth really quickly. Some days on flat ground it does the same thing. Sometimes I go for weeks and think oh I haven’t noticed that much lately. Other times I wonder how it hasn’t stranded me. Every time I have brought it up to the dealer when the car was newer and under warranty, they couldn’t get it to do anything. As they are in the city, I knew they wouldn’t. It’s bad enough that passengers look at me like what is going on. Everyone in the car can feel it.
 
The CVT is smooth and works fine in the city and a lot of times on the interstate, but there is a hill on the interstate on my way home that is a couple of miles long. For whatever reason the car jerks on that hill very frequently. It feels like the drivetrain is a bunch of rubber bands or like the computer is saying we need more power, no, no too much power, back and forth really quickly. Some days on flat ground it does the same thing. Sometimes I go for weeks and think oh I haven’t noticed that much lately. Other times I wonder how it hasn’t stranded me. Every time I have brought it up to the dealer when the car was newer and under warranty, they couldn’t get it to do anything. As they are in the city, I knew they wouldn’t. It’s bad enough that passengers look at me like what is going on. Everyone in the car can feel it.
That is strange, I wonder if it starts to ping and then backs off timing rapidly, then the trans reacts, and then timing goes back to normal, then pings again?
My uncle had a KIA Sorento that would do the same thing on the one long hill. But the dealer didn't send out a tech with real data logging either, so they never found out what was wrong, and it was the middle of the covid shortage so they just traded it in for not much extra money.
 
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