Grease is the Word
Oil Filter Study
Concentrating on the AC PF1218 and its equivalents
Including some Mercruiser, FL400s, and FL820s applications
With Pore and Flow Measurements
May 25, 2004
This oil filter study was originally started to determine if there was a better oil filter for the Mercruiser oil filter found on Chevrolet / Mercruiser inboard and I/O applications. It then grew to compare many manufacturers' equivalents to the AC PF1218. The AC PF1218 (and the Fram PH5) are used on a wide variety of vehicles particularly the GM V8.
The study was motivated and inspired by the discussions on the forums at Bob is the Oil Guy (BITOG). There you will find several forums discussing every aspect of lubrication and one dedicated to oil filters. The phrase above "Grease is the Word" is the author's screen name on the forums at BITOG. You can communicate with the author on BITOG via personal messaging or email.
This study could not have been completed without the help from many individuals, but mostly one BITOG member (who chooses to remain anonymous) that completed the bubble point and flow tests. He spent hours testing and retesting oil filter media. In fact, for this version (3) which added eight more media, he retested the original 12 filters to ensure that the testing was accurate.
Additional BITOG members provided financial support by donating money or filters:
Approximately 200 hours and about $150 have been spent on this project and has been about 6 months in the making to get to this point. This site requires $35 a year to remain on-line. If you have benefited from the material, please consider making a $1 Paypal donation to defer the cost of domain and web site costs. This will allow this site to remain on-line for longer than the first year.
Here are some definitions used throughout this study.
- ADBV - Anti Drain Back Valve; the pliable material used to seal the inlet holes so oil does not backflow.
- BPV - By-Pass Valve; a valve to allow oil to pass when oil is too thick or filter is clogged.
- Baseplate - the round plate at the base of the filter that mounts to the vehicle and contains inlet holes.
- Center Tube - the cylindrical tube in the center of the filter.
- Inlet holes - holes in the baseplate to allow oil to enter the filter.
- Filter top - the end of the filter away from the baseplate.
- Number of baseplate holes
- Area of baseplate holes
- Number and area of center tube holes
- Thickness of gasket
- Width of gasket seal
- Weight of entire filter
- Material of ADBV
- Number and location of welds
- Number of pleats on filter
- Effective Filter Area (EFA) of filtering media
- Material / design of spring
- Notes, positive and negative observations
In addition, the following measurements are made on the filter media:
- Average large pore size
- Smallest pore size
- Oil flow with Glycerin and 30W oil at 70F
The bubble point testing was performed using a similar bubble point tester to this unit.
This study concentrates on 18 AC PF1218 equivalents. These include the following filter models (in alphabetical order). The reader can click on a filter to show details, photos, and descriptions. Each link will open a new browser window. Within each filter page there are thumbnail pictures. To enlarge a picture, click on the thumbnail. To return to the specific filter page, click the back button on your browser.
- Amsoil SDF24
- Baldwin B1428
- AC Delco PF1218
- AC Delco UPF1218 *
- AC Delco PF35L **
- Donaldson P550964
- Fleetguard LF-3679
- Fram Extra Guard PH5
- Fram Tough Guard TG5
- Fram Extended Guard XG5
- Hastings LF279
- K&N HP-3002
- Mobil 1 M1-302
- Purolator PremiumPlus L34631
- Purolator PureOne PL34631
- STP S5
- SuperTech ST5
- WIX 51060
* The AC UPF1218 is no longer manufactured. It was included in this test to evaluate the media and provide a reference for the remainder of the UPF line still available.
** The AC PF35L is not a "true" equivalent since it does not have an ADBV. Otherwise it has the same dimensions as a PF1218. It was included in this test because of its synthetic media.
Two Mercruiser application filters are compared:
The media from three other filters are also tested and shown in the testing data spreadsheet.
- Donaldson Synteq media
- WIX Racing media (from S1515R)
- Parker Hydraulic filter #921999 a 20gpm filter with β10=2 efficiency (captures 50% of 10µm particles)
The Parker hydraulic filter can be used as a filtration benchmark because of its rated efficiency. Any of the filters above the Parker filter in the spreadsheet will provide better than 50% reduction in 10µm particles and any below it will provide less than 50% reduction in 10µm particles in a multi-pass test.
In addition, five filters representing the Motorcraft FL400s and FL820s are and shown in the testing data spreadsheet. While there are not pictures included of these filters, they do have their EFA, flow, and pore size calculated.
- Motorcraft FL400s
- Purolator PureOne PL20195 (FL400s)
- Purolator PureOne PL24651 (FL820s)
- Fram Tough Guard TG3600 (FL400s)
- Fram Tough Guard TG2 (FL820s)
In the filters above, the media was the same as their PF1218 counterparts. For example, the Fram TG2 media tested the same as the Fram TG5. The Fram TG2 EFA is then measured and compared to other FL820s filters.
Filter Testing Data
The tabulated data for this study can be found in MS Excel spreadsheet below (note: if you do not have MS Excel on your computer, you can download a free viewer from Microsoft using this link).
The intent of this study is to be as objective and non-biased as possible and just present observations. This data is collected in the above spreadsheet on two different tabs or worksheets. The first one is called Filter Data and contains physical measurements and observations. The second tab is called Bubble Point Testing and contains the results of the media pore size and flow tests.
Within the Bubble Point Testing tab filter names are either regular font, bold, or italics. The bold filters indicate an AC 1218 equivalent, and italics indicate a Mercruiser application (shorter canister to the 1218 filters).
Viscosity vs. Temperature
The tests in this study were done using 70F 30 grade oil. To give the reader a sense for how oil changes viscosity with temperature change, click here to view this chart that compares different oils at different temperatures.
Good construction, good flow, good filtering
In the low-priced group, the AC PF, Purolator PremiumPlus, STP, and SuperTech appear to be good choices. These four filters are "best buys" because they doing most things well and are in the low-priced group.
In the mid-priced group, the Baldwin and WIX appear to be good choices. Both have construction that is excellent.
In the high-priced group, the Amsoil, Mobil 1, Fram XG, and K&N appear to be good choices.
The Fram TG and Purolator PureOne have excellent filtering. They do flow less than filters with less filtering. Both are in the mid-priced group. The AC UPF also has excellent filtering, however, the UPF1218 is no longer manufactured. The UPF series does include other filter applications that are still available.
The Hastings, Donaldson, and Fleetgard all have excellent flow. Not surprisingly, they are also have larger pore sized media. The Purolator PremiumPlus and Amsoil flow less than these filters, but still better than average and have good or very good filtration.
The Mercruiser filter is a high-flowing filter with larger pore size. The WIX 51086 does not appear to be a good substitute in this application because it flows less than half as well as the Mercruiser. If one did not mind going to a longer format (the PF1218 style), other excellent candidates would be Hastings, K&N, and Purolator PremiumPlus. All three of these filters flow just as well or better than the Mercruiser, have better filtration, and give the added benefit of more media / increased sump capacity. The Amsoil would have to be another viable candidate since it filters much better than the Mercruiser and it flows almost as well.
Click here for more information regarding Mercruiser applications including additional filters and applications.
Disclaimer and cautions
Since many filter manufacturers contract out their filters, one must be careful that future filters from these vendors are the same as what is presented here. One way to do this is to compare the outside markings of new filters to these pictures.
Just because one filter appears to be a good choice for this application, does not mean that it will be the best for other automotive applications. Other applications involve by-pass valves and other features that may or may not make that same filter the best choice.