Engine Oil Filter Study

UPDATE:  To help reduce some of my email traffic from this page, I have created an FAQ.  Before emailing me with a question, please read the Oil Filter Study Frequently Asked Questions first.  I typically don't respond to questions that are already answered here.
 

Upcoming Filters

- AC Delco Ultraguard Gold PF2
- Amsoil SDF15
- Bosch
- Fram HP1
- Hard Driver HD01
- K&N Gold
- Penske
- Purolator HP1/L390001
 

Warning!

The primary shortcoming of this study is the small sampling size. I only tested the Ford 5.0L filter. It has come to my attention that some brand names use different manufacturers for different applications. Another shortcoming is the lack of testing of the filter element media itself. Unfortunately I have neither the time nor resources to do this.

I invite anyone with the means to take a larger sampling size and conduct a more complete study, which may include private SAE tests. I also invite anyone to repeat a study similar to this one on other model filters.

With all of that said, please make your own judgements. Use this study only as a source of some information that may give you a better idea about which filter brands to steer clear from. It should be obvious that some manufacturers are not being honest about their product. The next time you buy a filter for your car, buy two and hack one open to see what you have. My intent was to give you some information and alert you to some little-known issues, not to tell you what to think.

Description

AC Delco Duraguard PF2
AC Delco Ultraguard Gold PF2
AMSOIL SDF15
Baldwin B2
Bosch ???
Car And Driver SF-1A
Champ
Deutsch D539
Deutsch D545
Fram Extra Guard PH8A
Fram Tough Guard TG8A
Fram Double Guard DG8A
Hard Driver HD01
Mobil 1 M1-301
Motorcraft FL-1A
NAPA Gold 1515
Pennzoil PZ-1
PowerFlo SL30001
ProLine PPL-30001
Purolator Premium Plus L30001
Purolator Premium Plus L390001
Purolator Pure One PL30001
Quaker State Q58A
STP S-01
Wix 51515

I hope to add more brands to this study as I can acquire them. The analysis is sorted by brand name in alphabetical order. In each brand section, I have broken the information down into the brand name models, sorted by price. Pictures coming soon!

Disassembly and Measurements

The sections below detail each of the filters I tested. A summary of the measurements I took can be found in a table for each. I noticed that other filter part numbers for the same brand were designed a bit differently. This is probably because of the shape of the can and the requirements for that engine. Here is a description of each table entry:
 

The construction of the anti-drainback and bypass valves is an important feature. Many are made of nitrile rubber. As long as they have good sealing surfaces, they generally work fine. However, nitrile rubber diaphrams gets stiff in extreme cold and may fail to seal in those conditions. Silicone rubber seals or steel valves are not prone to this. Many bypass valves are spring-loaded steel and work well. Some are spring-loaded plastic and are often not molded well enough to make a decent seal, allowing oil to leak passed them.

Probably the most important value here is the element surface area. This helps determine the amount of filter media that is available to trap particles. Cellulose media (basically paper) can trap fewer particles and can flow less oil per square inch because there are fewer passages through it. Synthetic media has more passages and can trap more particles and flow more oil than cellulose per square inch. For the same type of media, the smaller the area, the sooner the filter will become plugged and will end up bypassing much of the oil instead of filtering it. Some filters use a cellulose/synthetic blend, so a direct comparison is not possible. More pleats in the element does not necessarily mean more surface area (as you will soon see). In fact, too many pleats can end up restricting the flow too much because there is not enough space between them to allow oil to flow. Most of the cheaper filters use a mix that is mostly cellulose. Some of the better filters use synthetics or synthetic blends. I'll try to come up with some way of identifyiong these.

The shell and backplate thickness are only relevant if your engine's oil system operates at unusually high pressures. Occasionally a seemingly strong filter can still leak due to a failure at the crimp between the can and backplate. If this happens to you, I would send it back to the manufacturer so that they can solve the problem. Even the cheapest filters have to be strong enough for stock oiling systems, or they will fail SAE tests.

I have removed SAE filtration efficiency and all other data that came from the manufacturers, since these are often inaccurate numbers.

Other measurements and values are debatable and I will allow you to draw your own conclusions from them.

SAE Tests

The SAE J806 test uses a single-pass test, checking for contaminant holding capacity, size of contaminant particles trapped, and ability to maintain clean oil. As an amendment of the J806 test, the multi-pass test also looks for filter life in hours, contaminant capacity in grams, and efficiency based on weight. The efficiency of the filter is determined only by weight through gravimetric measurement of the filtered test liquid. Typical numbers for paper filter elements are 85% (single pass) and 80% (multi-pass).

The SAE J1858 test provides both particle counting and gravimetric measurement to measure filter capacity and efficiency. Actual counts of contaminant particles by size are obtained every 10 minutes, both upstream (before the filter) and downstream (after the filter), for evaluation. From this data filtration ratio and efficiency for each contaminant particle size can be determined as well as dust capacity and pressure loss as a function of time. Typical numbers for paper element filters are 40% at 10 microns, 60% at 20 microns, 93% at 30 microns, and 97% at 40 microns.

NOTICE: Since all of the SAE data I have is from the manufacturers, it cannot be trusted to be truthful. Therefore all SAE data has been removed from the filter sections below.

AC Delco

Duraguard PF2

The telltale signs for an AC Delco filter are: Five large holes for the oil inlet and 6 spot welds on the rim surrounding them. There are no crimps holding the gasket in place. When you look through the inlet holes, you can see the metal bypass valve with its 12 small holes and the black anti-drainback valve diaphragm around it. Through the center outlet hole, you can see the spring for the bypass valve.

Exploded view:

AMSOIL

SDF15

Baldwin

B2

Bosch

?

Car And Driver

SF-1A

Champ

?

The Champion design has metal end caps on the filter cartridge, with the bypass valve stamped right into the bottom end cap like the Purolator. I refer to this as a one-piece filter cartridge. Though definitely not the same design as the Purolator, it does use the same type of leaf-spring-type spacer at the top of the cartridge and the nitrile anti-drainback valve, which doubles as the cartridge-to-backplate seal, at the bottom. One issue is that I sometimes noticed was some rust on the backplate of these filters. Since the rust is usually around by the inlet holes, any loose rust would be caught by the filter.

The telltale signs for a Champion filter are: 6 large holes for the oil inlet, one of which is larger than the others. Only the black anti-drainback valve can be seen through the inlet holes. There are 6 large crimps holding the gasket in place. Through the center outlet hole, you can see the bypass valve spring. Usually, the backplate metal is dull, or even rusty.
 

Deutsch

D539

D545

Fram

Fram Extra Guard PH8A

The telltale signs for a Fram Extra Guard are: It has 8 small holes for the oil inlet and a thin, cheap looking backplate, and is currently stamped with a "2Y". There are 5 very small crimps holding the gasket in place. If you look into the center hole all the way to the top of the filter, you will see a kind of "button" in the end cap of the cartridge (which looks like it's made of metal from there). This is the plastic bypass valve.

Exploded view:

Fram Tough Guard TG8A

The telltale signs for a Fram Tough Guard filter are: It has a better backplate that is usually shiny, with six larger holes for the inlet and 6 spot welds around the them. There are 6 large crimps holding the gasket in place. When you look through the inlet holes, you can see the orange anti-drainback valve. If you look into the center hole all the way to the top of the filter, you will see a kind of "button" in the end cap of the cartridge (which looks like it's made of metal from there). This is the plastic bypass valve.
 

Fram Double Guard DG8A

Although it has the lowest filter element surface area (193 sqin), it does have a clever spring-loaded nitrile rubber anti-drainback valve and bypass valve combination.

The telltale signs for a Fram Tough Guard filter are: It has a better backplate that is usually shiny, with six larger holes for the inlet and 6 spot welds around the them. The backplate should be stamped with a "1K". There are 6 large crimps holding the gasket in place. The anti-drainback valve diaphragm behind the inlet holes is black. If you look into the center hole all the way to the top of the filter, you will not see the "button" in the end cap of the cartridge (which looks like it's made of metal from there).
 

Hard Driver

HD01

Mobil 1

M1-301

It uses a synthetic fiber element that can filter out very small particles and is very strong. It is rated just under the Purolator Pure One as far as filtering capability, but is still very much above conventional paper filters. It also has a very strong construction to withstand high pressure spikes during start-up. However, as with all Mobil 1 products, expect to pay 2 - 3 times as much for this filter.

I have received many reports of these filters failing at high pressures. It seems that the seam where the backplate crimps to the case can split.

Exploded view:

Mopar

Oil filter Study Special Model Feature: Mopar

Motorcraft

Long Lasting FL-1A

Like the Purolator Pure One, this filter cartridge features a very large element surface area (400 sqin), but with many pleats (64). This packs the filter together rather tightly and may restrict flow somewhat. I could identify the Pure One element media by a purple dye they use at the seam. It also has the mysterious assembly string wrapped around the outside of the element. Like the Purolators, it features a spring-loaded metal bypass valve and a nitrile rubber diaphram-type anti-drainback valve. The bypass valve is stamped right into the bottom end cap of the cartridge, so it is all one piece.
 

NAPA

1515 Gold

51515 Silver

Pennzoil

PZ-1

All the measurements were exactly the same as the Fram Extra Guard PH8A.
 

PowerFlo

SL30001

ProLine

PPL-30001

<- With String - String Removed ->

As you may be able to tell, the string did not rip into the filter element, it only crushed it. There was no evidence that the element had been compromised. Out of the 8 Purolators (and clones) tested, this was the only one with a problem.
 

Purolator

Premium Plus L30001

Here is a fairly well designed filter, especially for the price. One odd thing about Purolator's filters is a string that is always wrapped around the filter element. I assume that this is there to hold the element in place while the glue in the end caps cures. Of all the Purolator-based filter I tested, there was one (the ProLine) that had filter element damage from this string. Although it was one of five tested, I am weary of this design. Even though the element was crushed a bit, it was not ripped. I will take apart a used one at my next oil change.

The filter cartridge has an impressive surface area of 316 sqin, which is very close to the AC Delco Duraguard. The difference is that Purolator's filter element is compressed into more pleats (51) than the AC Delco. This may restrict flow somewhat, but not as much in this model than the Pure One. It features a spring-loaded metal bypass valve and a nitrile rubber diaphram-type anti-drainback valve, which doubles as the seal between the backplate and the cartridge. Like the Champion, this bypass valve is stamped right into the bottom end cap of the cartridge, so it is all one piece.

The telltale sign for a Purolator filter are: 8 medium-sized holes for the oil inlet and nothing but a black (or orange for the Pure One) diaphragm to be seen through them. There are 6 large crimps holding the gasket in place. Through the center outlet hole, you can see the spring for the bypass valve.

Exploded view:

Pure One PL30001

The filter cartridge has an even more impressive surface area of 400 sqin. The potential issue is that this filter element is compressed into even more pleats (64) than the Premium Plus. This may restrict flow more than it helps relieve it. It also features a spring-loaded metal bypass valve and a silicone rubber diaphram-type anti-drainback valve, which doubles as the seal between the backplate and the cartridge. The bypass valve is located at the base of the cartridge, not at the top.
 

Quaker State

QS8A

STP

S-01

Wix

This filter has metal cartridge end caps, but has a separate bypass valve that rests against the bottom end cap, like the AC Delco. I refer to this as a two-piece filter cartridge. Like the Champion, it uses an anti-drainback valve that doubles as the bypass valve-to-backplate seal. Instead of the leaf-spring-type spacer that most filters use, these use a stiff coil spring at the top of the cartridge. Like the Purolator, the filter element paper media is stronger than the Champion media. The only drawback to this design is that the bypass valve seats metal-to-metal against the bottom cartridge end plate. This could allow dirty oil to seep from the dirty side to the clean side of the filter, bypassing the element. The design will not allow oil to seep back into the pan, though.

The telltale signs for a Wix are: 6 large holes for the oil inlet with only the black anti-drainback valve to be seen through them. There are 6 "notches" that hold the gasket in place. Through the center outlet hole, you can see the bypass valve spring. Usually the backplate metal is shiny.

51515

Conclusions

It should be clear that Mopar filters are really nothing special. Unless you are trying to have a perfect restoration and need that Mopar logo, there is no reason why you should be buying Mopar oil filters. Most of them seem to currently be Purolators or Champions, but that could change at any time.

See the AC Delco, Champion, Fram, Purolator, and Wix sections for information on how to identify these manufacturers by looking at the backplate. The tell-tale signs are always there.