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2020 Subaru Legacy 2.5L; M1 EP 0w20 21k mile OCI
- Thread starter iunderpressure
- Start date
Why?
Yeah, really…why?? OP definitely needs to find source of silicon entry, but it’s been there forever.
Other than that, no: viscosity concern, TBN concerns, fuel or coolant concerns… iron wear trending up just a hair compared to last sample, but at 1.5ppm/1k it’s hardly cause for alarm.
OP: all things considered, impressive run and fortitude. Are you using Fram Endurance?
That much silicon is almost certainly from dust. If the airbox looks clean, I'd start checking further downstream for leaks. A large enough leak downstream of the MAF sensor will cause high fuel trims that can be detected with an ODB scanner.
Dust will affect the piston rings more than anything else, and that might be why there's been some chromium in the oil on the two UOAs that had high Si. 1 ppm chromium might not seem high, but piston rings are pretty small and they might not contain much chromium on Subaru engines. The norm for most Subarus is 0 ppm, often with 1 ppm only on the first UOA on the factory fill during break in, when piston ring wear is a lot higher than normal.
Based on the low P:Zn ratio, it looks like there's some phosphorus loss. Some oxidative thickening has probably started on the 20k mile OCIs. The TBN is okay, but I'd say the oil is spent.
Did you use the FRAM Ultra in your signature for the entire OCI? I'd consider changing the filter at least every 10k miles, especially if the silicon issue isn't addressed. Either that or get another particle count done to see how it's holding up on these long OCIs.
If 40 ppm of the Si is from dust, that might amount to around 0.5 grams of dust in the oil. There could be a lot more than that amount in the filter, and then there's all the wear metal, carbon, etc, that will need to be filtered on a long OCI. The Ultra XG7317 has a decent holding capacity at 6.7 g, but might start bypassing at <5 g on this engine due to its low bypass setting.
Dust will affect the piston rings more than anything else, and that might be why there's been some chromium in the oil on the two UOAs that had high Si. 1 ppm chromium might not seem high, but piston rings are pretty small and they might not contain much chromium on Subaru engines. The norm for most Subarus is 0 ppm, often with 1 ppm only on the first UOA on the factory fill during break in, when piston ring wear is a lot higher than normal.
Based on the low P:Zn ratio, it looks like there's some phosphorus loss. Some oxidative thickening has probably started on the 20k mile OCIs. The TBN is okay, but I'd say the oil is spent.
Did you use the FRAM Ultra in your signature for the entire OCI? I'd consider changing the filter at least every 10k miles, especially if the silicon issue isn't addressed. Either that or get another particle count done to see how it's holding up on these long OCIs.
If 40 ppm of the Si is from dust, that might amount to around 0.5 grams of dust in the oil. There could be a lot more than that amount in the filter, and then there's all the wear metal, carbon, etc, that will need to be filtered on a long OCI. The Ultra XG7317 has a decent holding capacity at 6.7 g, but might start bypassing at <5 g on this engine due to its low bypass setting.
I used one Fram Ultra for the entire OCI. I thought of using the Endurance next change, but isn't the filtering more course?
I live on a gravel road which was pretty dusty. The good news is my road within the last few weeks has been chip and sealed, so no more dust.
My last OCI, was the first time using M1 EP, so this run should be pure M1 EP. That's why I think the TBN and some of the other numbers could be a little higher than the last run.
I have also had the Thermo Control Valve replaced at 99,737 miles. To replace the part they had to remove the intake manifold.
I live on a gravel road which was pretty dusty. The good news is my road within the last few weeks has been chip and sealed, so no more dust.
My last OCI, was the first time using M1 EP, so this run should be pure M1 EP. That's why I think the TBN and some of the other numbers could be a little higher than the last run.
I have also had the Thermo Control Valve replaced at 99,737 miles. To replace the part they had to remove the intake manifold.
The Endurance should be more efficient. All of the particle counts I've seen for Amsoil filters are very good, and those filters are pretty much identical to the Endurance. The Ultra seems to produce higher particle counts, especially for smaller particles.
The Endurance might actually have a lower dirt holding capacity, but the FE7317 has an 11 psi bypass, vs 9 psi for the XG. The Endurance is the better filter, but I would change it just as often as I would the Ultra.
I'm guessing that work caused a vacuum leak somewhere.
The particle count I got on one of the early samples was using the Royal Purple filter which is the same basic filter too.
The other I believe was the Wix.
The other I believe was the Wix.
FWIW, the one particle count I've seen for an OEM Tokyo Roki filter was 16/16/13, which is pretty respectable. Not as good as an Endurance would do, but much better than the WIX and better even than most PCs I've seen for the Ultra.
The Tokyo Roki filters have a lot of media, so they should have a good holding capacity, and they've got the higher bypass pressure as well. They should be a lot more resistant to clogging and bypassing on a long OCI than the Endurance, and seem to be better than the Ultra at pretty much everything.
Wow, a 30000km OCI seems a bit extreme for me, but that would be about once a year for us... I guess you are doing lots of hwy driving to get up around 35-40k miles a year? What kind of mileage do you get?
I live 56 miles from my work, so that’s at least 112 miles each day that I work. All but 3 or 4 miles of that is highway. A day or two per week I do some extra city driving.
I haven’t figured mileage by hand lately, but this summer the computer is usually around 32 mpg. I want to say the winter is closer to 30.
I haven’t figured mileage by hand lately, but this summer the computer is usually around 32 mpg. I want to say the winter is closer to 30.
IRON, look at your report!
The iron is fine. It's just 30 ppm in a 21k mile sample. (1.42 ppm / 1k miles)
That's an excellent wear rate. The Fe content is nowhere near the condemnation point on wear metals.
Your feelings about extended intervals don’t trump the data. OP has gradually worked his way up in mileage, and other than the silicon level there’s nothing wrong here.
Go ahead and change your oil every 3k. This Subaru is obviously doing quite well at 140k+. If OP gets his silicon source identified and fixed, there’s zero concerns with 20k intervals especially if a C&P of the filter shows no particulates on the surface of the media.
BTW @iunderpressure, have you been servicing your CVT? If so, what fluid?
I do 5k intervals, and let me know when he reaches 300,000 miles following those intervals. If you think UOA tells the full story you are misinformed.
Oxidation/TAN would be helpful. Wear looks really good. Hard to complain about this UOA.
What's the oil consumption history on this car? I'd be concerned about piston deposit buildup on the rings going that long on an oil for consecutive intervals. However it may be completely fine with no buildup.
What's the oil consumption history on this car? I'd be concerned about piston deposit buildup on the rings going that long on an oil for consecutive intervals. However it may be completely fine with no buildup.
Is this Subaru engine DI?