How to evaluate oil filter quality

You speak of the need for a good high quality oil filter, but you don’t provide any specific guidance... and, in my experience, there’s a lot of variability in oil filters these days (much more variability than for oil, other than the new oils which are being labeled “extended service/miles”).

Is a “good quality” oil filter the pricey Mobil 1 and K&N Filters and their ilk? (The one’s with 99%+ multi-pass ratings/extended service ratings, and high prices to match??) Or the upgraded Fram’s of the world (Tough Guard/Extra Guard/Extended Guard)?, or Purolator Pure One, etc. (less expensive, but with excellent multi-pass ratings?) Or will any oil filter with a 96% first pass rating meet your criteria for “good quality”? (the base Frams, Purolators, etc.)

And which is the better rating to use if one adheres to your (still-squeamish?) advice for extended oil change intervals? First pass, or multi-pass efficiency ratings?? (I would think multi-pass is more important for extended oil change intervals than single pass, but not all filters provide multi-pass ratings!). And finally, what about “high mileage” oil filters? (Fram HM’s, etc., the ones with "stuff" in the middle of them?)

Thanks. Jim

Good Question, actually multiple questions! One specific answer; don't expect to get quality for nothing, you get what you pay for. Single pass filter testing is useless unless you intend to change the filter every 100 miles. Multi-pass testing provides realistic testing for the application of the filter.

Filters are rated for efficiency (at a specific micron level), life (holding capacity) and flow rate (GPM through the filter). Additionally, filter canning is rated for burst pressure and some filters are designed with bypass valves and some are not. Micron ratings can be manipulated by using lighter weight or heavier weight oil in the test, so honesty is the watchword. If you are using 5,000 mile oil changes then capacity is not an issue and you should concentrate on efficiency and micron ratings.

When looking at efficiency some filter companies use "nominal" ratings which are 50% ratings, meaning the filter removes 50% of the particles of a particular size. Other filter companies use actual efficiency ratings like 80% or 97% etc. When you see the term "absolute" it means greater than 97% efficiency. Amsoil EA filters are made from nano-fiber technology and are the best filters available. The nano-fiber technology was developed by Donaldson Co (huge filter company).

Amsoil is able to sell to light truck and auto markets because Donaldson sells primarily to large trucks and heavy equipment markets. Using a high quality filter is a vital component of your lubrication system and using poor but cheap filters will ultimately be very expensive. Dirty oil is abrasive and the abrasive nature of the oil will cause accelerated wear and premature engine failure.

Dan Watson

FAQ - Filtration