I’ve been using the FRAM Ultra XG12447 on my 2025 GMC Yukon with the 3.0L LZ0 Duramax. Based on the ISO 4548-12 testing published by Ascent Filtration Testing, I had viewed the Ultra as probably the efficiency king for this application.
With First Brands in liquidation and the future of Champion/FRAM filter production uncertain, however, I no longer see the current Ultra as a dependable long-term option. Even if production returns under new ownership, there is no guarantee that it will remain the same filter.
That sent me down the rabbit hole of trying to find the next best PF66-compatible filter. The problem is that the published efficiency information is all over the place. Some manufacturers give an efficiency percentage at 20 microns, others use 25 or 30 microns, and some provide no meaningful micron-specific information at all. That makes an honest comparison based on the advertising nearly impossible.
Since I would have liked to see a comprehensive comparison myself, I started buying the filters. My eventual plan is to cut them open and compare their construction, media area, pleat consistency, valves, component dimensions, workmanship, and whatever reliable manufacturer specifications are available. I realize that a teardown cannot reveal actual filtration efficiency, but it should still tell quite a bit about how the filters are designed and built.
I initially wasn’t going to include all of the “20K” and extended-performance filters because I suspected some might prioritize capacity and service life over finer filtration. By the time I had purchased most of the others, though, I decided it would be more useful to include them and make the comparison as comprehensive as reasonably possible.
Here is what I currently have on hand:
I have not tried to purchase every jobber or installer-grade filter. At this point, I am mainly trying to determine whether I have overlooked any significant consumer filter, unusual design, or distinct manufacturing source.
I am also aware of the PF66B and PF66C. The PF66C was not listed in the GM parts catalog for purchase. I ordered a PF66A and PF66B through GM, but they supplied two PF66As instead. The PF66A and PF66B apparently are treated as interchangeable Silver-series filters in the GM ordering system.
Is there anything important I’m missing before I consider the collection complete?
Please also let me know if I have a bad cross-reference, an incorrect or superseded part number, or an obvious duplicate being sold under another label.
Once the remaining filters arrive and I settle the inventory, I’ll make a follow-up post outlining the measurements and observations I’m considering before I start cutting them open.
Also, one date-code observation that may help others:
One useful thing I found while assembling the collection concerns the date codes on the Vietnam-made filters. Several filters share the suffix 8748, have very similar external construction, and appear to come from VAFI in Vietnam.
Based on the codes from my filters, several older Premium Guard photo examples, and a VAFI pre-shipment inspection report dated September 3, 2020 I found on the internet, the format appears to be:
YY|”M”|[last letter of month][first letter of month]|DD|”8748”
Examples:
The month code appears to use the last letter of the month followed by its first letter: RO for October, RN for November, RD for December, HM for March, and so forth. January and July both appear to produce YJ, so those two require context.
I have not seen this date-code format documented elsewhere, so I would be interested to know whether anyone has seen additional examples or has factory information that confirms it.
With First Brands in liquidation and the future of Champion/FRAM filter production uncertain, however, I no longer see the current Ultra as a dependable long-term option. Even if production returns under new ownership, there is no guarantee that it will remain the same filter.
That sent me down the rabbit hole of trying to find the next best PF66-compatible filter. The problem is that the published efficiency information is all over the place. Some manufacturers give an efficiency percentage at 20 microns, others use 25 or 30 microns, and some provide no meaningful micron-specific information at all. That makes an honest comparison based on the advertising nearly impossible.
Since I would have liked to see a comprehensive comparison myself, I started buying the filters. My eventual plan is to cut them open and compare their construction, media area, pleat consistency, valves, component dimensions, workmanship, and whatever reliable manufacturer specifications are available. I realize that a teardown cannot reveal actual filtration efficiency, but it should still tell quite a bit about how the filters are designed and built.
I initially wasn’t going to include all of the “20K” and extended-performance filters because I suspected some might prioritize capacity and service life over finer filtration. By the time I had purchased most of the others, though, I decided it would be more useful to include them and make the comparison as comprehensive as reasonably possible.
Here is what I currently have on hand:
- ACDelco PF66
- ACDelco PF66A
- ACDelco Gold Ultraguard UPF66R
- Baldwin B40162
- CarQuest Premium 95146
- CarQuest Extended Performance P95146
- FRAM Tough Guard TG12447
- FRAM Ultra XG12447
- FVP R0351
- K&N HP-1021
- Luber-finer PH10066
- MicroGard MGL10351
- MicroGard Select MSL10351
- Mobil 1 Extended Performance M1-115A
- NAPA Gold 100351
- NAPA ProFormer 2100351
- Parts Plus PH10066
- Premium Guard PG99495
- PPE MicroPure 114000650
- ProTec PXL10351
- Purolator L11424
- PurolatorONE PL11424
- PurolatorBOSS PBL11424
- Purolator 20K LX12447
- STP S45008
- STP Extended Life S45008XL
- WIX WL10351
- WIX XP WL10351XP
- NAPA Platinum 6100351
- Donaldson P584944
- aFe Pro Guard HD 44-LF047
- Champ PH10066
- ECOGARD X11715
- ECOGARD Synthetic+ S11715
- FRAM Drive FD12447
- FRAM Extra Guard PH12447
- FRAM Force FF12447
- FRAM Titanium FS12447
- Hengst H832W
- MAHLE OC1660
- Mighty M9510
- PurolatorTECH TL11424
- Service Champ OF1424
I have not tried to purchase every jobber or installer-grade filter. At this point, I am mainly trying to determine whether I have overlooked any significant consumer filter, unusual design, or distinct manufacturing source.
I am also aware of the PF66B and PF66C. The PF66C was not listed in the GM parts catalog for purchase. I ordered a PF66A and PF66B through GM, but they supplied two PF66As instead. The PF66A and PF66B apparently are treated as interchangeable Silver-series filters in the GM ordering system.
Is there anything important I’m missing before I consider the collection complete?
Please also let me know if I have a bad cross-reference, an incorrect or superseded part number, or an obvious duplicate being sold under another label.
Once the remaining filters arrive and I settle the inventory, I’ll make a follow-up post outlining the measurements and observations I’m considering before I start cutting them open.
Also, one date-code observation that may help others:
One useful thing I found while assembling the collection concerns the date codes on the Vietnam-made filters. Several filters share the suffix 8748, have very similar external construction, and appear to come from VAFI in Vietnam.
Based on the codes from my filters, several older Premium Guard photo examples, and a VAFI pre-shipment inspection report dated September 3, 2020 I found on the internet, the format appears to be:
YY|”M”|[last letter of month][first letter of month]|DD|”8748”
Examples:
- 25MRO18 8748 = October 18, 2025
- 25MRN25 8748 = November 25, 2025
- 25MRD19 8748 = December 19, 2025
- 26MHM31 8748 = March 31, 2026
- 26MLA14 8748 = April 14, 2026
The month code appears to use the last letter of the month followed by its first letter: RO for October, RN for November, RD for December, HM for March, and so forth. January and July both appear to produce YJ, so those two require context.
I have not seen this date-code format documented elsewhere, so I would be interested to know whether anyone has seen additional examples or has factory information that confirms it.
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