Many people are concerned about using aftermarket oil filters and often stick to OEM filters, assuming that they offer the least chance of "issues" with the filter or with warranty coverage.

An Understandable Assumption

In some respects, I can understand and even somewhat agree with this sentiment. It is often true that dealers will push OEM filters REALLY hard, to the point where they will even imply or even directly state that your warranty could be voided if you use non-OEM filters.

Can You Say "Criminal"

This is an illegal practice. If a dealer tries to require you to purchase an OEM filter, remind them that federal law states they must provide that filter to you for free unless the vehicle manufacturer has successfully proven to the FTC that ONLY use of their brand filter will adequately protect the vehicle in question.

Since I am aware of NO OEM filter for which this is true, they either need to back off or they need to give you the filter. Obviously, the chances of them giving the filter to you for free are pretty slim, since the whole reason they are pushing that OEM brand is to increase profits.

What About Construction Quality Issues?

It is "generally" true that large OEMs offer fairly well constructed filters that are relatively well quality controlled, which provides a fair assurance of few "issues" with your filters, such as stuck bypass or anti-drainback valves, etc. However, you're never going to be immune to the possibility of a stuck bypass or anti-drainback valve, I don't care whether you use OEM or not. No manufacturing process is perfect. Defects happen. Just look at the bikes and vehicles we're putting these filters on.

Bypass Valve Function

As far as the valves are concerned, the working of the bypass valve is only going to be a significant issue if the oil is really cold or if the filter has been in service too long and has become saturated.

If the oil is really cold and "thick" (which is primarily going to be an issue if you're running petroleum oil or heavier weight oils in your auto or bike), then it will have a harder time passing through the filter media. Pressure may build to the point where the bypass valve needs to temporarily open in order to maintain adequate oil flow, until the oil warms up.

If the filter has been in service too long and has become saturated to the point where the oil can no longer flow adequately through the media, the bypass valve should then REMAIN open all the time to maintain adequate oil flow, until the filter is changed. You can tell if an oil filter is saturated by CAREFULLY attempting to touch it after running the engine for a bit, when the oil should be hot.

Obviously, be very careful not to burn yourself, but, the idea here is that, if the filter media has become too saturated, the bypass valve will be open (or at least should be). With the bypass valve opens, the oil isn't passing through the media. In this case, the filter will not get as hot as the oil. Often, in these cases you can pretty much grab the filter, and it won't be hot enough to burn you.

So, if you can grab or touch your filter after a drive without burning yourself, the filter has likely gone into bypass mode and needs to be changed. Of course, you ideally want to change the filter long in advance of this point, but this is a simple test to make sure you're not leaving your filters on too long.

Anti-Drainback Valve Function

The anti-drainback valve can be pretty important if you're running petroleum oil, since it tends to "run off" very quickly once an engine is shut down. Therefore, if an engine running petroleum oil has been sitting for even 5 or 10 minutes, but especially if it's been hours or days, there is virtually no oil film left on your engine components, which means, at start-up, your engine is running metal on metal till the oil gets from the pan to the upper areas of the engine.

The anti-drainback valve serves the purpose of keeping oil in the filter, which puts a certain quantity of oil that much closer to engine components, shortening the time that the engine is running metal on metal until the oil gets to where it needs to be. So, this is a critical valve if running petroleum oil (and still a valuable one if using synthetic).

But, if you're running a premium grade synthetic oil, it may cling to your engine components MUCH longer (often for many hours or even days or weeks - depending upon the type of basestocks used). This is specifically true if the synthetic you're using has a small amount of ester basestock in it. Ester basestocks are especially tenacious in terms of clinging to engine components. This provides a film of protection at start-up, preventing metal to metal contact until oil from the pan reaches the upper areas of the engine.

A short digression from our topic ...

You don't, in my opinion, want a fully ester basestock unless the engine never sits in cold and/or humid climates and is always run up to operating temp very quickly to burn off any condensation in the oil. If this is not the case, since esters are prone to hydrolysis, where the water is actually absorbed into the oil - a fully ester basestock is not likely a good choice for you.

It is better to utilize an oil which is a good blend of multiple PAO/ester basestocks. Every basestock type has it's benefits and drawbacks. None is perfect in and of itself. Therefore, careful blending of the natural positive and negative aspects of numerous basestocks provides a method for improving the overall performance of the oil while minimizing the negative characteristics of any one of the basestocks by themselves.

At any rate, back to the topic of discussion. An anti-drainback valve is especially critical if running petroleum oil. Not AS cricitical if you're running a synthetic oil, especially one that is using a small amount of ester basestock in the oil. However, that doesn't make it UNimportant, only LESS critical.

Either way, a good functioning anti-drainback valve is very helpful and a malfunctioning one is not good.

AfterMarket Filters More Prone to "Problems"?

I suppose it is probably true that aftermarket filters, as a whole, are probably more prone to problems with valves and seals than most OEM filters, but this is only because you've got some pretty crappy aftermarket filter companies who pay far too little attention to quality control and often use low-quality filter components while selling the filters for a premium price - achieving HUGE profit margins.

In truth, there are auto and motorcycle OEMs out there who are also selling crappy OEM brand oil and filters but asking a premium price simply because their name is present on the can. Just because an oil or filter has the OEM name on it doesn't make it high quality. BUT, if you use an OEM brand oil or filter and something DOES go wrong, you'll likely have an easier time with warranty issues. I think it would be disingenuous for any aftermarket filter manufacturer/dealer to suggest otherwise.

No Problems or Better Overall Protection?

All of the above being said, the primary question that remains, is whether, at the end of the day, you're protecting your vehicle better with an OEM filter or with an aftermarket filter. Is it more important to simply avoid potential filter construction/quality problems and warranty issues or is it more important to be using a high efficiency, high capacity filter.

The answer is .... NEITHER! They are BOTH important. Not only do you want a filter that is constructed of high quality materials and under strict quality control measures, you also want one that is constructed of the proper TYPE of media that will offer the greatest efficiency and capacity to protect your engine at all times.

Does it really matter if it's OEM or aftermarket? No. Does it, possibly, make your life easier to just choose to purchase the OEM brand filter? Maybe. But is it the best stewardship of your resources? Are you doing everything you can to protect your expensive vehicle from premature wear and failure?

Assuring High Quality in an Aftermarket Filter

Let's assume that you choose to go with an aftermarket filter company. How do you know you're getting a filter constructed of quality materials? Quite frankly, the best way to know is to cut the thing apart. Open it right up. Try opening up a new one AND an old one.

How is the media itself? Is it sturdy? Does it have a wire mesh backing for stability? How about the resin that's used to hold the cellulose media together? Does it seem to be holding - before AND after use?

Are the endcaps metal or cardboard (you'd be surprised at who uses cardboard endcaps in their filters). How thick is the metal sheeting used for the filter housing? The thicker it is, the better it will be able to withstand a high pressure situation.

Find a filter that offers high quality materials AND high efficiency/capacity media, and you've got the "perfect filter", regardless of the brand or whether it's OEM or Aftermarket.

What About Quality Control?

Of course, using high quality components is great, but, if there is minimal quality control, components may be compromised even before manufacturing begins. Moreover, if there is not quality control within the manufacturing process itself, numerous defects in workmanship can sporadically materialize.

This is precisely why ISO certification is important. ISO standards are validated quality standards. ISO 9001:2000 is the most widely utilized quality standard throughout the world for quality management systems.

ISO 9001:2000 is applicable to any manufacturing and service organization providing a framework for system development that focuses on the customer, quality system performance and ongoing improvement.

So, check the ISO certification of the company you're going to get your filters from. Is their certification up to date? Are they certified at all? If not, you should question their quality control measures and think twice about purchasing their filters.

But, What About Filter Capacity & Efficiency?

Now, with all of that being said regarding quality control practices, we have still not gotten around to a DETAILED discussion of filtration efficiency and capacity which are so critical to everyday engine protection.

Many OEM brand filters are still using cellulose based filter media (while the structural components are normally of good quality to prevent "failure"). This is not true of ALL OEM oil filters, but many of them.

As such, their filtering efficiency and capacity are not nearly comparable to a high end, high efficiency oil filter using synthetic and possibly even the newer nanofiber media technology to not only increase efficiency but also capacity.

Capacity is an issue in the sense that, the lower the overall capacity of the filter, the sooner it will need to be changed. So, if the filter is being saturated with particulate and it offers low capacity, it won't be long before the bypass valve needs to open to maintain oil flow.

As long as this valve is open, oil flow is maintained, but no filtration is occurring, thus, dirty oil is circulating throughout the engine. If the media is saturated and the bypass valve fails, little if any oil flow is maintained and oil starvation will occur.

So, function of the bypass valve is important, but filter capacity is also important if you're not changing your filter very regularly because it can have just as much affect on oil flow. Many OEM filters are not super high capacity filters. Thus, they should be changed fairly frequently to avoid having them end up in "bypass mode".

Certainly, there are high capacity filters on the market. But, of course, filter capacity is really only a factor in establishing HOW LONG a filter can be effectively used to remove engine oil contaminants. It really has no bearing on how WELL the oil is filtered.

That is where filter efficiency comes into play, and this is also a very important issue, which, intuitively would make sense, but many people I don't think put enough weight on this issue.

In paper 881825 the SAE indicates that a joint study was performed between AC Spark Plug and Detroit Diesel Corp. The study found that finer oil filtration significantly reduced the rate of engine wear.

According to the paper, the tests regarding engine wear within gasoline engines were run at 40 microns, 30 microns, 25 microns and 15 microns (diesels were tested as well, at somewhat different micron ratings with similar results).

The researchers had this to say:

"Abrasive engine wear can be substantially reduced with an increase in filter single pass efficiency. Compared to a 40 micron filter, engine wear was reduced by 50 percent with 30 micron filtration. Likewise, wear was reduced by 70 percent with 15 micron filtration."

Most cellulose media based filters offer an absolute filtration rating of 40 microns - some as low as 30 but not many. A high efficiency synthetic media filter generally will offer absolute filtration efficiency at least as low as 25 microns, with at least one offering absolute filtration efficiency down to 15 microns.

According to the study, moving from a 40 micron cellulose media filter to a 15 micron synthetic media filter, engine wear would be reduced by 70%.

In fact, although it takes a little extra math to figure this out, even if you give cellulose media filters a generous 30 micron absolute efficiency rating you'd still see a 40% decrease in engine wear by moving from a cellulose media filter to a 15 micron synthetic media oil filter.

This is not filter company propaganda. Detroit Diesel had no vested interest in trying to show high efficiency oil filters to be better than cellulose media filters. That's just how the testing came out.

So, the question is, how much is that 40% or 70% decrease in engine wear worth to you? Is it worth taking the time to REALLY investigate the issue a bit to find a filter that offers you the qualities you need? Is it worth paying a bit more for your filters in order to get those qualities? I think so, but, you'll have to make your own decisions when it comes to the protection of your own vehicle.