Any reason NOT to run 15K OCI with M1EP on a Subaru NA 2.5 boxer (80% highway) ?

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NO2

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Using M1EP 0w-20 with Fram Ultra. The 12K warranty on a short block replacement is up. So far the oil consumption is around 1/4 qt in 7500 miles. We take weekly of highway trips of 30-250 miles so I doubt that fuel dilution is an issue. Not a GDI engine.

Mobil claims 15K (old) and 20K(new) between oil changes with M1EP.

Given this usage, is there any real reason not to go with 15K OCI's?
 
I would say under those particular conditions and oil choice are top for extending drains, however verify via a UOA at some point. You'll have (1)qt of makeup oil at that rate which is beneficial.
 
Short block replacement makes me think it's a FB25 or FB20. There have been some UOAs posted here on the FB Subaru engines, they seem quite capable of 10k or more mile OCIs.
 
Just because the oil bottle or filter box says you can go XX,XXX miles, that doesn't mean that you should for your use case. Manufacturers will sell you the absolute maximum under best case scenario.

The fine print on both will usually say something to the effect of "If your vehicle is covered by a warranty, follow the vehicle's oil life sensor or the oil change interval recommended in your owner's manual. Proper maintenance practices, including frequently checking the oil level to ensure that the appropriate amount of oil is present, are required to ensure effective performance."

Start with the OCI recommended in your owner's manual and get a UOA done to see if you can extend your OCI from there. A UOA will give you more concrete evidence about how a specific oil interacts with your engine and your operating conditions.
 
NO2 said:
Using M1EP 0w-20 with Fram Ultra. The 12K warranty on a short block replacement is up. So far the oil consumption is around 1/4 qt in 7500 miles. We take weekly of highway trips of 30-250 miles so I doubt that fuel dilution is an issue. Not a GDI engine.

Mobil claims 15K (old) and 20K(new) between oil changes with M1EP.

Given this usage, is there any real reason not to go with 15K OCI's?
Click to expand...
Yes.
Low tension piston rings.
 
Put in what ever oil you choose. If you get the feel good feeling because you put the top rated, best quality, EP oil in your vehicle, that's all fine.
Manufacturer probably says inferno circumstances to exceed more than 10,000mi between changes. Or they suggest following the OCI. USA combination of different driving I don't know of any that routinely go beyond 10,000 miles.

ever since the internal combustion engine was invented and motor oil was needed there's always been the argument that dirty motor oil it's not too far from the truth of being liquid sandpaper.
How good is your oil filter? How good do you trust it?

I use a good quality oil and I still will never run more than 10,000 miles between an oil change. our religiously maintain my vehicles by the time the OC light gives me a warning that tells me I should plan to change my oil it's probably already done.

I say I seldom ever exceed 7500 to , 8500 between changes. Right now I'm using Castrol Edge EP. Yes I went for the best only because it was on roll back and I believed over stocked at my local Walmart.
Normally I use Mobile AFE or PP. Whichever is cheaper.
 
Last edited:
Subaru don't like M1? But, If you find out what they like, please let me know.
I figured out the care and feeding of a EJ253 and FB20 but the FB25 remains a mystery. It seems to want more HTHS than a 20 but not all of a 30. Maybe a candidate for the old 1 quart of 5W30 and balance of the 0W20. I ran EP in a FB25, It seemed to like it: Noisy, but powerful - at least from the passenger seat perspective.
That same engine got the SoA dealer consumption test. Surprisingly and magically, it stopped consuming large amounts of oil. I asked the service writer, what did you put in there? "Just regular bulk oil sir" At the tim,e that was PEAK 0W20 with a Danica Patrick photo on the bottle. The engine clattered on the oil loudly when it got hot, but ran well for trips of 15 miles or less.

Q: How long is you 80% highway trip one way daily? How many miles per year?
I would stick to 10K given my two UOA on the more reliable and quieter FB20 motor
Good luck. - Ken
 
Before blindly diving into murky water I'd want to know how deep it is, and what lies below the surface. Translation: A 15K OCI is a long run, no matter what the label on the oil bottle says. I'd take a sample at the halfway point via the dipstick tube and send it off for a UOA. Then determine how much further you could safely go.
 
Ahhj back to the Blackstone UOA! Why would you pay for this? Their cheapest analysis is $30. Just change the oil. Never understood why anyone takes the times to produce a sample and send it off for analysis. For the less than the cost of the analysis I can change the oil and filter .

Some you would rather spend a dime to save a nickel.
 
ARCOgraphite said:
Subaru don't like M1? But, If you find out what they like, please let me know.
I figured out the care and feeding of a EJ253 and FB20 but the FB25 remains a mystery. It seems to want more HTHS than a 20 but not all of a 30. Maybe a candidate for the old 1 quart of 5W30 and balance of the 0W20. I ran EP in a FB25, It seemed to like it: Noisy, but powerful - at least from the passenger seat perspective.
That same engine got the SoA dealer consumption test. Surprisingly and magically, it stopped consuming large amounts of oil. I asked the service writer, what did you put in there? "Just regular bulk oil sir" At the tim,e that was PEAK 0W20 with a Danica Patrick photo on the bottle. The engine clattered on the oil loudly when it got hot, but ran well for trips of 15 miles or less.

Q: How long is you 80% highway trip one way daily? How many miles per year?
I would stick to 10K given my two UOA on the more reliable and quieter FB20 motor
Good luck. - Ken
Click to expand...
For the EJ253 (and most others) Mobil 1 5w30 ESP is the one. 5K OCI.

These are the ones Mobil recommend in Germany for the 253. The 5w30 ESP is the best all round choice followed by 0w30 ESP and FS 0w40, the LV 0w30 ESP and X1 are good short trip around town oils. The 3000 is your basic old car oil ready to head to the big bone yard oil.


recommendations

www.mobil.com.de www.mobil.com.de
 
We have an '13 FB25 engine. We drive around 250mi 1x per week, and 30-50 mi 2x per week. The other driving is local - 2-10 miles, with an 80% highway, 20% city mix. According to Subaru, the oil consumption issues on the '13 2.5 were related to defective rings, and the FB25 does not have head gasket issues like the older EJ series. The highway miles are all 75-80 mph.

I have a Honda 3.0 J30A5 V6 in an Accord which shows 4k+ more life on this same oil (no makeup) at around 13-14K, according to Blackstone. That is used for shorter 10 mi commutes and driven 50-100mi 2x per week. Honda engines are easy on oil. How hard are Boxer engines on oil?
 
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