In addition to my “opinion” rating of the filters, I am attempting to rate the filters based on a scoring system. This is also opinion based, but it provides details to the reasons for my opinions of the different filters. The scores are generated by breaking the filters down into various factors that influence the overall rating and then weighting the factors to achieve an overall score. Here is how I see the various factors and how they figure into the overall rating.

Cost – 20 points

This is straight forward. This factor is worth 20 points. I subtracted the cost of the filter from 20 to calculate the score for this factor. The highest score goes to the Pro-Tec 159 (18.5) and the lowest to the Amsoil Ea011 (4.25). The Motorcraft FL-820S scored 16.72. You might chose a lower rating for this factor, or dismiss it altogether if you want the best filter regardless of cost.

Filter Can Quality – 3 points

There is very little difference in the various filter cans. And this is a relatively unimportant category. All of the filters were either a 3 or a 2. In most cases, if the can used 0.020” thick material, I rated it a 3. If it was less, I rated it a 2. Even though the Amsoil Ea011 Filter had a 0.020” thick can, I rated it a 2 because it had no features to make installation easier (no flutes, flats, or easily gripped surface). The FL-820S scored 3 points in this category.

Base Gasket Design – 3 points

This is another minor category. Most filters were awarded either 1 point or 2 points. I gave the Denso 150-1014 3 points because of its innovative gasket design. All the other filters used similar square section O rings. If the O ring included a lubricant, I awarded the filter 2 points in the category. Otherwise it got 1 point. The FL-820S scored 1 point in this category.

Inner Core Design – 3 Points

I preferred the inner core design of the Purolator, Wix, and Amsoil filters and gave them all 3 points. The other filters that used a metal inner core (including the Motorcraft FL-820S) got 2 points. The Champion labs filters that used a plastic inner core got 1 point.

Retainer Spring Design – 3 points

I prefer the coil spring type retainer. I feel it will be more consistent in providing consistent pressure on the filter element and give the best seal between the filter element and base. Filters that use a coil spring retainer got 3 points. All the others (including the FL-820S) got 2 points.

Anti-Drain Back Valve Design – 15 points

I consider this a very important factor for Ford Overhead Cam Engines. It is probably less important for the old OHV engines. If you ahve an OHV engine you might want to drop this factor from 15 to 10 points. I rated the  ADBVs based on material and design. The Amsoil EaO11 Filter had the best design (in my opinion) and I gave it 15 points. The FL-820S had the next best design and got 14 points. Most of the other “premium” filters with silicone ADBVs were given 11 or 12 points. The Donaldson P550965 had a ADBV similar in design to the Amsoil EaO11but it was molded from nitrile instead of silicone. Therefore I gave it only 10 points. The filters that used the combination ADB and Relief Valve design (Wal*Mart and STP) got the lowest score of 3 points.

Relief Valve Design – 10 points

This is a hard category for me to score. All the filters I have evaluated, except for the Motorcraft FL-820S, have a dome end relief valve design. The FL-820S relief valve is far more elaborate and expensive than the relief valve design used by any of the other filters. So why does Ford go to all this trouble for a relatively inexpensive filter, while all of the other premium filters, including filters that cost 4 times as much make do with a dome end relief valve? I don’t know the answer. I do believe the base end design is the best (well except for the cheaply made combo valves). Interestingly, several of the other manufacturers admit that the base end design might be required by some manufacturers. It seems to me that Ford, by the design of their OEM Filter, is making this a requirement. I can only assume it is not written into the product specifications, since all of the premium filters are claimed to meet OEM specifications. I gave the FL-820S filter 10 points in this category. The filters with the coil spring loaded dome end filter element relief valves got 5 or 6 points. The Fram filters got 3 and 4 points (the TG2 got 4 because of the screen – I am not sure this is justified). The Bosch filter got 3 because I just don’t like the design. The cheap filters with the combined ADB and relief valves got 2 points. If you don’t think the relief valve design or location is particularly important, you might want to rescore this category.

Media - total of 40 points, broken down into four 10 point sub-categories

Now we come to the most important categories. These are the ones that actually relate to the filter media. I don’t have the means to actually test the media; therefore this is a beauty contest more than an actual performance contest. This is the only way I can rate the . I love to hear a suggestion on a better rating method. Rather than have one overall score for the media, I have broken it down into 4 sub-categories worth 10 points each – media volume, media surface area, filter element construction quality, and filter media quality. Therefore the media represents 40% of the total score. This might not seem like enough since the primary purpose of the oil filter is to filter the oil, but the filters don’t differ greatly in the other categories, so the media categories taken together are the deciding factors.

Media Volume – 10 points

This was a straight forward calculation. The filter with the most total media, the Ford Racing CM-6731-FL820 FIlter was awarded 10 points. The other filters were award points based on their total media volume compared to this. The FL-820S got 8 points. The Amsoil EaO11 was only awarded 5 points. I am worried this comparison is not fair to the EaO11 Filter. All of the other filters had media that was either cellulose or cellulose blended with “synthetic” fibers. It may be that the Amsoil media is so different, a direct comparison of volume is irrelevant.

Media Surface Area – 10 points

More surface area equates to higher flow rates and more contaminant holding ability. The Ford Racing CM-6731-FL820 FIlter was awarded 10 points in this category since it had the greatest surface area. The other filters were award points based on their total media surface area compared to this. The FL-820S was awarded 6 points in this category. Again, because of the unusual media, I am not sure I am being fair to the Amsoil EaO11 Filter (it scored only 4 points).

Filter Element Construction Quality – 10 points

The Amsoil EaO11 Filter has a very well constructed filter element and I awarded it 10 points. The Donaldson filter element was the same as the Amsoil filter except for the media, so I awarded it 10 points as well. The FL-820S was slightly better made (mostly because of the interface to the ADBV) than the “premium” filters that used metal end caps and was awarded 8 points. All of the other filters that used metal end caps and a glued media seam were awarded 7 points. The Denso filter also was awarded 7 points despite using a metal clip to make the media joint. The Fram filters were awarded 4 points and this was generous given the low quality appearance of the paper end caps and the use of a metal clip to make the media joint. The Wal*Mart and STP filters were awarded 3 points. I just don’t like the poorly bonded fabric end caps.

Filter Media Quality – 10 points

This was strictly my opinion. I liked the Amsoil media and awarded it 10 points. I awarded the FL-820S 8 points. The “premium” filters all got 7 to 9 points. The lowest rated fitler was the Pro-Tec 159 which got 4 points.

And the Winner is…..

I was a little surprised by the results. With cost considered, the Motorcraft FL-820S was the highest rated filter, but not by much. Here are the results:

Filter Mfg	Filter P/N	Total Score (with cost)	Total Score (without cost)
---------------------------------     ----------------------------		---------	-----------
Motorcraft	FL-820S	81	81
Motorcraft	MFL-820	80	79
Ford	CM-6731-FL820S	80	91
Wix	51372	78	78
Purolator	PL24651	77	79
Donaldson	P550965	76	78
Denso	150-1014	72	79
Purolator	L24651	72	69
Fleetguard	LF3681	71	69
Pro-Tec	159	71	66
Fleetguard	LF16002	70	75
Bosch	3410	70	70
ProLine	PPL-24651	69	65
Advance Auto	AA2	69	65
Mobil 1	M1-210	68	73
C. G. Enterprises	Viper 2	68	65
Amsoil	EAO11	67	78
K&N	HP-2010	66	73
Hastings	LF110	66	66
Fram	TG-2	65	64
Fram	PH-2	58	52
Wal*Mart	ST2	57	49
STP	S2	56	49
AC Delco	PF1250	55	49

For the Total Score (without cost) column, I just removed the cost factor and normalized the result to 100 points. Clearly the Amsoil filter was hurt by its high cost when compared to the FL-820S. but even if you ignore cost, I scored the FL-820S slightly higher. This is entirely due to the small size of the filter element in the Amsoil EaO11 Filter. The filter media may be much better than the media in the FL-820s, but is it 60% better? I don’t have an answer. But, until I see an independent test proving that this media is far better than the conventional media used by the other filter manufacturers, I can’t justify spending 4 times as much (or more) for the Amsoil EaO11 Filter. If you really like the syntheic media used in the Amsoil EaO11 Filter and can live with a nitrile anti-drain back valve, then the Fleetguard LF16002 might be worth a look. It appears to use a lot more of a similar media and costs half as much. Unfortunately the LF16002 has a nitrile anti-drain back valve, and not even a particularly well designed one.