🔴💊 Engine Oil Red Pill Thread: Only Post If You Have UOA - Official Honda Civic Type R K20C1 Engine Oil Analysis

[jtlctr]

i got to change my oil filter again. changed my oil last week but the Honda filter i used wobbled a bit as i threaded it on. guess the threads weren't cut 100% straight or something. Also got a rattle sometimes on startup like the anti drainback valve isn't sealing.

anyways, makes me nervous, so bought a new one.

anyone ever ran into a Honda filter with a manufacturing defect? bought this one from the dealer

I have not heard of anything like that, but anything is possible. Did you install the new filter yet? And did the rattle stop?

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[cryptolime]

I have not heard of anything like that, but anything is possible. Did you install the new filter yet? And did the rattle stop?

only noticed the top end rattle a couple times when restarting for a second (hot engine). maybe leaky ADBV

goin to put a new filter in for peace of mind. I'll take some pics of the sketchy one. first questionable quality Honda filter I've encountered.

 

[zumbooruk]

Honda OEM filter 15400-PLM-A02 was manufactured by Fram (and a cheap low end Fram).

Fram went belly up last year

from recent search, it seems that Honda now sources 15400-PLM-A01 from Filtec for North America. and 15400-RTA-003 Mahle Tennex for Japan/Global.

Since Honda used a cheap low end Fram, I don't really trust Honda's selection of filters...

I did a lot of research as far as filtering efficiency, micron size, pressure drop, oil flow, bypass, etc. (did not care about "dirt holding capacity" or milage rating, since I change at 5,000)

Either Mobil 1 or Purolator Boss seem to be best, with Mobil 1 slightly better in filtration efficiency

 

[cryptolime]

I've heard good things about WIX. but, these filter companies seem to always be changing manufacturers every few years so quality is all over the place

Mann (W6103) and Mann is supposedly good too.

 

[zumbooruk]

I've heard good things about WIX. but, these filter companies seem to always be changing manufacturers every few years so quality is all over the place

Mahle is supposedly good too.

Difficult for me to make a decision. I am always striving for "perfection", yet sometimes there is no "perfection" only best compromise...

I just repeated my spec research.

These come up on top: Amsoil, Mobil 1, Purolator Boss, Wix.

Amsoil filters a bit better, but has a bit more oil restriction compared to Mobil 1.

Purolator Boss seems to have updated their spec and now claimed filtration efficiency is slightly better than Mobil 1

but since I am not sure if the new specs are for new production, or just revised specs

Amsoil is not as easy to get

for now I'll stick for Mobil 1 for my next oil change (already purchased one last week... )

I believe I cannot go wrong with any of the above.

 

[johnloov]

I did have a small honda Dallas dealership somehow install the honda filter and break the oil filter, or maybe it was faulty, and it leaked, but probably human error as they had also under-filled the oil, and didn’t screw in my under tray. This is a very interesting topic on oil filters. Curious what is best that flows equal to oem, but with better filtration, and higher quality.

 

[zumbooruk]

I did have a small honda Dallas dealership somehow install the honda filter and break the oil filter, or maybe it was faulty, and it leaked, but probably human error as they had also under-filled the oil, and didn’t screw in my under tray. This is a very interesting topic on oil filters. Curious what is best that flows equal to oem, but with better filtration, and higher quality.

Amsoil seems best. followed by Purolator Boss and Mobil 1

Filter	Filtering Efficiency (ISO 4548-12)	Effective Micron Rating (99% capture)	Pressure Drop	Oil Flow	Bypass Valve Pressure
Honda 15400-PLM-A01 (OEM Filtech/Toyo Roki)	~99.9% @ 20 µm (per supplier data)	~20 µm	OEM moderate (cellulose media)	OEM-optimized (good)	~8-14 psi (spring-loaded)
Honda 15400-RTA-003 (OEM equiv. Mahle Tennex)	~51-95% @ 20 µm (varies by test)	~25-30 µm	OEM moderate	OEM-optimized (good)	~8-14 psi (spring-loaded)
Amsoil EA15K20	98.7-99% @ 20 µm	~20 µm	Very low (nanofiber synthetic)	Excellent (lowest restriction)	~12-17 psi (OEM-matched)
Purolator Boss PBL14610	>99% dirt removal (SmartFUSION full synthetic)	~25 µm	Low (reinforced synthetic)	Excellent (double-helix tube)	14-18 psi
Mobil 1 M1-110	99% @ 30 µm (synthetic blend)	~30 µm	Low-moderate	Very good	14-18 psi

Values collected from the following sources

Honda 15400-PLM-A01
Filtering efficiency ISO 4548-12: ~99.9 percent at 20 µm. Source: Filtech/Toyo Roki supplier data quoted on HRV Forum (thread from 2016).
Effective micron rating 99 percent capture: ~20 µm. Source: Same supplier data above.
Pressure drop: OEM moderate (cellulose). Source: Design comparison in cut-open videos and BITOG analyses.
Oil flow: OEM-optimized (good). Source: Honda engineering match for K-series pressure curves.
Bypass valve pressure: ~8-14 psi. Source: Honda forum consensus and direct measurement threads (BITOG 2008 thread lists similar A02 at 14 psi).

Honda 15400-RTA-003 (Mahle Tennex)
Filtering efficiency ISO 4548-12: ~51-95 percent at 20 µm (varies by test). Source: Amsoil independent ISO test graph in EA Oil Filters bulletin G2192 (shows PLM-A02 at 51 percent).
Effective micron rating 99 percent capture: ~25-30 µm. Source: Inferred from Amsoil test data and Mahle OEM specs.
Pressure drop: OEM moderate (cellulose). Source: Same as above.
Oil flow: OEM-optimized (good). Source: Honda K-series calibration.
Bypass valve pressure: ~8-14 psi. Source: Equivalent to PLM-A02 measurements in YouTube cut-opens and BITOG threads.

Amsoil EA15K20
Filtering efficiency ISO 4548-12: 98.7-99 percent at 20 µm. Source: Official Amsoil product bulletin G2192 and current Amsoil.com spec sheet (explicit ISO 4548-12 rating).
Effective micron rating 99 percent capture: ~20 µm. Source: Same Amsoil bulletins.
Pressure drop: Very low (nanofiber synthetic). Source: Amsoil flow-restriction comparison chart in the same bulletin.
Oil flow: Excellent (lowest restriction). Source: Same nanofiber media data.
Bypass valve pressure: ~12-17 psi Source: Amsoil design spec for Honda fitment.

Purolator Boss PBL14610
Filtering efficiency ISO 4548-12: >99 percent dirt removal (SmartFUSION synthetic). Source: Official Purolator product page and packaging claims.
Effective micron rating 99 percent capture: ~25 µm. Source: Purolator technical data referenced in product specs and BITOG cut-open threads.
Pressure drop: Low (reinforced synthetic). Source: Purolator double-helix center tube design bulletin.
Oil flow: Excellent (double-helix tube). Source: Same Purolator engineering specs.
Bypass valve pressure: 14-18 psi. Source: Crossfilters.com product listing for PBL14610.

Mobil 1 M1-110
Filtering efficiency ISO 4548-12: 99 percent at 30 µm (synthetic blend). Source: Official Mobil.com product page for M1-110A.
Effective micron rating 99 percent capture: ~30 µm. Source: Same Mobil.com spec.
Pressure drop: Low-moderate. Source: Synthetic blend comparison on Mobil site.
Oil flow: Very good. Source: Same.
Bypass valve pressure: 14-18 psi (~16 psi typical). Source: Mobil spec sheets.

 

[zumbooruk]

did more research, turbochargers need finest filtration since they spin so fast.

I found one more source from 2021 by Ascent Filtration evaluation using ISO 4548-12 which measured Purolator Boss actual performance at 87.79 percent efficiency at 25 microns and only 61.80 percent at 20 microns.

These results placed it behind Fram Ultra, Royal Purple, and ACDelco Gold in efficiency at 20 microns and larger particles.

Fram Ultra was the best at 99.96% at 20 microns, but unfortunately, Fram is no more.

https://ls1tech.com/forums/advanced...6-iso-4548-12-oil-filter-efficiency-data.html

https://speed-talk.com/forum/viewtopic.php?t=63818

Ascent did not test Mobil 1, and I was not able to find any other independent test for Mobil 1.

researching more about the Royal Purple filter, which was second to the Fram

 

[zumbooruk]

updated results, this time using independent testing over manufacturer claims

seems Royal Purple might be the best, yet seems out of stock every where I looked. including Royal Purple direct.

Filter	Filtering Efficiency (ISO 4548-12)	Effective Micron Rating (99% capture)	Pressure Drop	Oil Flow	Bypass Valve Pressure
Honda 15400-PLM-A01 (Filtech/Toyo Roki)	~51-70% @20μm (older est.; no recent Ascent)	~25μm est.	Moderate (good OEM baseline)	Good / low restriction	~13-14 psi
Honda 15400-RTA-003 (Mahle Tennex)	Similar to PLM-A01 (~51-70% @20μm est.)	~25μm est.	Slightly higher than PLM-A01	Good	~13-14 psi
Amsoil EA15K20	98.7% @20μm (ISO 4548-12, mfr)	20μm	Low	Excellent (nanofiber)	~8-17 psi (typical EA series)
Purolator Boss PBL14610	61.8% @20μm (Ascent independent)	~34μm	6.82 psid @30 LPM	Good	14-18 psi
Mobil 1 M1-110	99% @30μm (mfr)	30μm	Lowest in class	Excellent	14-18 psi
Royal Purple 10-2867	99.08% @20μm (Ascent independent)	~20-25μm	8.84 psid @30 LPM	Moderate / higher restriction	11-17 psi

 

[Ktrw]

I believe purolator rates the purolator one filter at bit higher efficiency than the boss versions. Since most of us don't need the capacity for 15k mile oil changes that may be one worth looking into.

 

[cryptolime]

updated results, this time using independent testing over manufacturer claims

seems Royal Purple might be the best, yet seems out of stock every where I looked. including Royal Purple direct.

FilterFiltering Efficiency (ISO 4548-12)Effective Micron Rating (99% capture)Pressure DropOil FlowBypass Valve PressureHonda 15400-PLM-A01 (Filtech/Toyo Roki)~51-70% @20μm (older est.; no recent Ascent)~25μm est.Moderate (good OEM baseline)Good / low restriction~13-14 psiHonda 15400-RTA-003 (Mahle Tennex)Similar to PLM-A01 (~51-70% @20μm est.)~25μm est.Slightly higher than PLM-A01Good~13-14 psiAmsoil EA15K2098.7% @20μm (ISO 4548-12, mfr)20μmLowExcellent (nanofiber)~8-17 psi (typical EA series)Purolator Boss PBL1461061.8% @20μm (Ascent independent)~34μm6.82 psid @30 LPMGood14-18 psiMobil 1 M1-11099% @30μm (mfr)30μmLowest in classExcellent14-18 psiRoyal Purple 10-286799.08% @20μm (Ascent independent)~20-25μm8.84 psid @30 LPMModerate / higher restriction11-17 psi

what about the 15400-PLM-A02? that's the most common

 

[cryptolime]

only noticed the top end rattle a couple times when restarting for a second (hot engine). maybe leaky ADBV

goin to put a new filter in for peace of mind. I'll take some pics of the sketchy one. first questionable quality Honda filter I've encountered.

got the old filter out. inspected it and didn't see anything obviously wrong. but, with a new filter installed, there's no more start-up rattle and engine is quieter

 

[jtlctr]

got the old filter out. inspected it and didn't see anything obviously wrong. but, with a new filter installed, there's no more start-up rattle and engine is quieter

OK, I guess I’ll be using my last OEM filter for a gearshift knob or something. Thanks for the heads up!

If you get bored, you should cut the old filter open to see if anything looks amiss.

 

[cryptolime]

OK, I guess I’ll be using my last OEM filter for a gearshift knob or something. Thanks for the heads up!

If you get bored, you should cut the old filter open to see if anything looks amiss.

i need to get an oil filter cutter

 

[zumbooruk]

what about the 15400-PLM-A02? that's the most common

The 15400-PLM-A02 was manufactured under contract by Honeywell/Fram (the blue-can version which was cut open and compared to Fram PH7317 Extra Guard).

Fram’s parent company (First Brands Group) did file Chapter 11 bankruptcy, and Fram filters are no longer available, thoush

Which is why I did not compare it as I assume that it is no longer available like other Fram made filters.

Yet it seems that Honda still has a large stock of the A02


In March 2026 First Brands agreed to sell the Fram brand name, trademarks, patents, engineering know-how, and related intellectual property assets for 12 brands to Premium Guard Inc. (PGI), but it seems that the original Fram factories are permanently closed and being liquidated. PGI will probably sell their own filters under the Fram brand name

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