Oil filter studies – don’t believe everything you read

If you’re a motorhead you’ve probably seen the online oil filter studies where a self-proclaimed “non-lubrication expert” cuts apart oil filters to compare their construction. In my opinion, that “study” is short on actual testing and filled with assumptions and projections that have little to do with oil filtration. The study has an obvious bias against FRAM oil filters. It shows through the entire study.So, let’s take a look at the study “findings.”

Inlet holes

First, the study makes a point of discussing the small oil inlet holes on FRAM filters. But if you’re a car buff, you know that oil pumps are designed to build lots of pressure, but they actually pump very little VOLUME. That’s because oil pumps are a gear displacement design. They work by compressing oil in the very small void between two gear teeth. Simply put, you can’t pump a lot of oil in that small gap. And engines don’t need a lot of oil volume. If they did, 4-5 quarts wouldn’t be enough to keep the pan level high enough as the oil is being pumped up to the head and drizzling back down. So the whole point about small inlet holes, in the real world, is basically bogus. You don’t need large inlet holes.

The Square Inch Theory Doesn’t Measure Up

Next the study compares the number of filter media pleats and square inch count of the media itself. Now a rational person would read this and automatically assume that more filter media means better filtration. But that depends on the filter media's efficiency. Before you guys jump off a cliff on this one, you should know that there are over 75 different types of filter materials out there. Each one has different filtering characteristics. And that doesn't even cover the proprietary filter media developed specially for a filter manufacturers. If a filter media with a larger surface but poor efficiency, it will larger particles through. In that case, what good is all that surface area? I’ve looked through the “studies” and keep coming up empty on the results for any filter media efficiency testing. I wonder why the study didn’t actually TEST the filter media to measure its filtration efficiency. Without that data, the study seems to be standing solely on a “more square inches is better theory” Until we know the efficiency of the filter media, the number of pleats and total surface area is irrelevant.

Of course, even if we did have efficiency ratings, the next question is, “How much surface area is enough?” Ah hah! There’s no good answer to that. Because even if we assume that you change your oil and filter religiously every 3,000 miles, it’s the condition of YOUR ENGINE, what kind of AIR filter YOU use and how often YOU change it (which is based on actual conditions—not mileage), what type of driving YOU do, the operation of the PCV valve* (see footnote 1), and YOUR overall engine performance (worn spark plugs and wires produce more misfires) that determines just how much junk ends up in the oil and the filter. If you really take care of your car, drive “right” and install a filter with the lowest square inches of filter media, you may actually have more than enough filtering protection. That would make the study’s assumptions irrelevant—which is my point. More on how much is enough later in the story.

End Plate Thickness

Really, I almost laughed out loud on this one. The end plate is what threads onto your engine. It pulls the rubber gasket up to the mating surface. As the gasket meets the mating surface, it compresses. As long as the end plate keeps the gasket compressed, it has done its job. Extra thickness beyond what is necessary to hold the gasket against the mating surface is simply useless. I’ve seen plenty of oil filters leak at the gasket area—but the leaks are ALWAYS caused by over torqueing the filter and splitting the gasket, or installing the new filter over on top of a stuck gasket from the previous filter. Bottom line, the whole end plate discussion is bogus. The question is really, how much thickness is enough. And the answer is: It has to be thick enough to compress the gasket—period. Anything thicker is a waste. My take on the end plate thickness discussion is that it’s useless information that doesn’t contribute to the quality discussion at all.

End Cap Construction is a You-Get-What-You-Pay-For Issue

Now we’re talking turkey. Let’s say we have a filter material that’s very efficient and the pleats are well formed. But if the oil rides up or down towards the end caps and those end caps aren’t sealed properly, it’s all for nothing. The oil will take the path of least resistance and seep past the end caps and down the center tube. It won’t open the bypass valve. It will go between the pleats and the end cap. Here’s the bottom line, regardless of which filter manufacturer you look at, they all make cheap filters for the economy-minded consumer. And cheap filters have cheap end caps. It’s that simple. One of the “better” manufacturers in this “study” makes a private label filter for a large retailer. Cut that puppy open and you’ll find fiber end caps glued to the pleats. Do they work? Yup. Will they last 7,000 miles? Doubtful. But they’ll probably do just fine for 3,000 miles. So it doesn’t make any sense to compare the construction of a $9 filter to a $3 filter. If you fill your crankcase with expensive synthetic oil and slap on a cheap filter, well, don’t be surprised that the filter won’t go the distance—regardless of which brand you choose.

Anti-drainback valve construction is also related to filter price.

Nitrile is cheap. Silicone is more. Guess which material a manufacturer will use for the anti-drainback valve on a cheap filter? Do you need silicone? Maybe. If your filter is mounted sideways or at an angle on the engine, the oil in the filter will drain back into the engine at shutdown unless it’s stopped by the anti-drainback valve. An empty filter means a delay in building pressure at startup—the most critical time for an engine. So the anti-drainback valve can be very important, depending on where your filter is mounted and how long you keep it in service. If your filter mounts end-plate-up, the whole anti-drain back valve issue is a moot point—oil doesn’t drain straight up. Nitrile anti-drainback valves DO harden up and lose their sealing ability as they age. So if you don’t change your oil on time AND your filter is mounted at an angle or sideways, quit being a cheapskate and buy a filter with a silicone anti-drainback valve. All cheap filters have nitrile valves. Silicone valves are either orange or grey. Just look through the oil inlet holes and check the color. Enough said?

The Story of the Lonely Bypass Valve

The bypass valve is like the Maytag repair man--it's idle most of the time. Its job is to bypass oil past the filter media if the media is plugged.* (See footnote 2) What does it do the rest of the time? Nothing. When does the filter get plugged? When the oil is loaded with crud. Why is the oil loaded with crud? Because YOU don’t change your oil on time and you don’t take care of your car. If you don’t care enough to maintain your car, why do you care if the oil is bypassing the filter?

Seriously folks, this one is a no-brainer. I read the studies and I can’t find where anybody actually TESTED the bypass valves to see if they leaked. Instead the study seems to rely on a letter from a guy who says he worked for FRAM years ago. That guy says the bypass valves were molded from plastic and they weren’t formed well. The guy didn’t sign his letter because he’s afraid of being sued. Do we know if his information is real? Nope.

FRAM manufacturing plants meet ISO 14001 and ISO/QS 9000 quality certifications. Don’t know what ISO quality standards are or who ISO is? Read this:

“ISO (International Organization for Standardization) is the world's largest developer and publisher of International Standards.

ISO is a network of the national standards institutes of 161 countries, one member per country, with a Central Secretariat in Geneva, Switzerland, that coordinates the system.

ISO is a non-governmental organization that forms a bridge between the public and private sectors. On the one hand, many of its member institutes are part of the governmental structure of their countries, or are mandated by their government. On the other hand, other members have their roots uniquely in the private sector, having been set up by national partnerships of
industry associations.

Therefore, ISO enables a consensus to be reached on solutions that meet both the requirements of business and the broader needs of society.”

For more information on ISO, go to www.iso.org

So here we have a study that was conducted by a “non-lubrication expert” who cuts filters apart in his basement but doesn’t actually perform any tests, and a letter from an obviously disgruntled former FRAM employee. On the other hand, we have an international standards organization that certifies quality at every major manufacturer. Who are we to believe? If you don’t think ISO certification is important, then perhaps you discount the fact that Champion Labs is also certified by ISO. Is their certification bogus too? Don’t get me wrong. Champion Labs makes great products and they also make really inexpensive filters under private label for large retailers. We owe them and FRAM the benefit of the doubt that they’ve tested their filters in real world conditions and the filters passed the tests in order to gain ISO
certification. To me, that’s a more important indicator of quality than a study that’s biased against FRAM—a study that apparently didn’t actually perform any tests. (Feel free to correct me if I’m wrong about that point)

Is there a High Mileage Hoax?

The filter study really bashes the High Mileage filter by FRAM. Is a high mileage additive a gimmick? All the major oil manufacturers seem to offer high mileage oil. Are they in on the same scam? I said I’d get back to this when we discussed how much filter media is enough. Now is the time.

Oil is clean when you pour it in. But then it gets dirty. How? Well, first, no matter how new your engine is, combustion gasses ALWAYS seep past the piston rings. That’s right, piston rings aren’t a continuous circle. There’s always a gap. So the high pressure of compression forces combustion gases through all 3 piston ring gaps and into the crankcase. That gas is called “blow-by.” The makeup of blow-by gases varies depending on the condition of the engine and the efficiency of the burn. If you have worn spark plugs, you’ll have more misfires. That will put more UNBURNED gasoline and soot into your crankcase. The gasoline will wash sediment off the internal engine parts. The soot grinds away at metal parts, like bathroom cleanser. The oil carries the sediment, soot, and crud to your oil filter (But that’s only if you haven’t depleted all the dispersant additives in your oil. If you have, then all that crud will settle to the bottom of your oil pan where it will form SLUDGE). If your plugs are in good shape and the engine is running at high efficiency but you do lots of short trips, you’ll end up with a lot of condensation in your crankcase. What are many engine components made from? Yeah, steel. Water + steel = rust. Water + combustion gases= acid. Oil contains anti-corrosive additives to fight rust and neutralizers to combat acid. But if you run your oil past it’s expected life OR make short trips, OR your engine has a lot of miles, YOU WILL DEPLETE THOSE ADDITIVES AT A FASTER RATE. High mileage oil has more of these additives. Don’t use high mileage oil? Maybe you could add those additives back into your oil by installing a high mileage oil filter. Ah, so FRAM isn’t so crazy after all.

Now let’s take a look at the study’s complaint about the FRAM High Mileage filter and the plastic gel holder. The complaint is that the gel capsule obstructs oil flow. When the filter is new, hot oil flows through the pleats and down the center tube. But if the gel capsule is blocking the return of the oil, the oil filter should pressurize and blow up, right? Or, it should pressurize and blow the gel into the oil pump, right? But that doesn't happen. Why?
Because the study’s assumptions are WRONG.

As the hot oil flows down the center tube, it DOES hit the top of the gel. But then it rolls down the BACKSIDE of the pleats. It exits the oil filter through the holes in the bottom of the capsule—the holes that aren’t blocked by the gel. Over time, as the gel dissolves, it opens more holes. Once it’s completely gone, the oil goes straight down the center tube. If you’re following me, you see that the whole point of this design is to force the hot oil to hit the gel and then flow around it as it dissolves it. If the flow rate for oil was 20 gallons per minute, maybe he’d have a point about the obstruction. But remember, engine oil is high pressure, low flow rate. So, if you own a high mileage vehicle and want to replenish acid neutralizers, anti-wear additives, and dispersants, the gel capsule is a great way to do it. Plus, buying a high mileage oil filter is actually cheaper than buying 5 quarts of high mileage oil. Don’t like the gel idea? Fine. Don't buy it. But don't follow the study’s biased assumptions and bogus theories about oil obstruction when they aren’t true.

There is a bottom line to this.

Every filter manufacturer makes high and low end filters. Want a high end filter? Great! Spend more and buy one that’s made with synthetic glass/cellulose filter media, mesh pleat backing, a metal core tube, metal end caps, silicone anti-drainback valves, and spring operated bypass valves. Oh, and buy a filter from a manufacturer that’s ISO rated for quality.

As for an oil filter “study” that doesn’t actually test the efficiency of the filter--well, take that for what it's worth. It's an opinion piece, sprinkled with a few irrelevant facts.

My disclaimer

I do NOT work for FRAM. I do not make any money off of FRAM. They're a large filter manufacturer owned by an even larger and extremely well respected manufacturer (Honeywell). Honeywell makes lots of electronics components for the automotive industry. They also own Prestone. They own Bendix brakes. They’re a major player in the automotive industry. They are one of the largest manufacturers of heating and air conditioning controls in the world. In short, they're no slouch outfit. I wrote this opinion piece because I didn't think the oil filter study was nearly as objective the authors would have us believe. And, I saw lots of people quoting from it as if it were the "bible."

Always remember this: Never believe anything you read on the Internet--not even my stuff. This is all my opinion. Don't take it as anything more than that. Now take a deep breath and read the footnotes

1. In the old days, car makers let blow-by gases run out a tube on the back of the engine. Blow-by gasses create smog. They contain soot. In other words, they pollute. What to do with blow-by gases if you can’t eliminate them? Yeah, burn them. So car makers suck the blow-by gases out of the crankcase and into the intake manifold. Wouldn’t that create a vacuum inside the engine? Yes, except that car makers allow fresh FILTERED air in to replace the gasses that were sucked out. See where I’m going? If you don’t change your air filter or you have a leak in the air duct, you suck DIRTY air into the crankcase. If you drive in dusty conditions, you can bet you’re going to suck in more dust. Where’s the PCV in all of this? Well, the job of the Positive Crankcase Ventilation valve is to close off the route from the intake to the crankcase in the event of a backfire. But since the PCV is always sucking blow-by gases and some oil vapor, it can clog up and restrict the flow. When that happens, more crud stays in the crankcase. How do you test a PCV? Shake it. If you hear a sharp metallic sound, it’s good. If it feels mushy, chances are it’s gunked up and should be replaced. Unsure? Replace it. They’re cheap.

2 There are times when the bypass valve can open even if the filter isn’t clogged. Multi-viscosity oil is supposed to flow well at low temps. But flowing well at -20° is a relative term. There are instances where cold oil can build oil pressure inside the filter casing to the point here it forces the bypass valve open. However, once the oil heats up, the bypass valve should close because the bypass spring pressure will be greater than the resistance offered by the filter media. The real question is this: if the oil is cold and thick at startup, is it carrying contaminants that should be filtered? Maybe so, if the there’s crud on the bottom of the oil pan. But if you’ve ignored oil changes to the point where you’ve got that sludge buildup, why do you care if the bypass valve is open. Your engine will be toast soon anyways.

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