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Lots of talk across a bunch of threads all over the forum regarding oil filters. Instead of posting on one thread here and there I am just going to make a new thread here instead of a generation/model year specific forum.
I am not making any recommendations to use any filter over another, I am just trying to share some knowledge. While I strive to be thorough and accureate, I am not infallible and I make no guarantees.
I also may ramble a bit, so sorry in advance.

So what do we really know about the purportedly special SkyActiv filters? There are at least 3 different PNs which reportedly reflect location of manufacture as Japan, Thailand, and Mexico. The PN is also different than the older Mazda filter. There are no specs to be had for either the new or old Mazda parts to compare. About all we know is that the SA filter has no ADBV (anti drainback valve).

On the aftermarket side; there is a split with some using a new PN and some calling for the existing PN. And there is some specs available on these (thank you Wix and Rock Auto).The key differences shown by Wix comparing a 1995 MX6 to a 16 SA filter is the bypass setting and the height.
The bypass valve for 2016 is between 37 & 75% greater, and the height for 1995 is 20% higher.
Both filters have specs stating there is less than a 2psi drop at 4gpm.

If all else is equal with the internals...
The 20% difference equates to 20% more volume and area.
In hydrodynamics, smooth flow pressure drop is inversely proportional to pipe size. In a turbulent environment, however, it is inversely square- so that 20% increase in volume quickly becomes a 44% reduction in pressure drop.

But all else being equal is not the case...
The ADBV is going to generate some turbulence; but the pressure drop on a clean filter has the same specs, so does not appear to be a concern.

Then there is viscosity; changes are proportional here as well, thicker oil will have a higher pressure drop.
When the old filter spec (whatever it was) was created, we were commonly using 10w30 (at least in the states). Now we are using 0w20.
 
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Lots of talk across a bunch of threads all over the forum regarding oil filters. Instead of posting on one thread here and there I am just going to make a new thread here instead of a generation/model year specific forum.
I am not making any recommendations to use any filter over another, I am just trying to share some knowledge. While I strive to be thorough and accureate, I am not infallible and I make no guarantees.
I also may ramble a bit, so sorry in advance.

So what do we really know about the purportedly special SkyActiv filters? There are at least 3 different PNs which reportedly reflect location of manufacture as Japan, Thailand, and Mexico. The PN is also different than the older Mazda filter. There are no specs to be had for either the new or old Mazda parts to compare. About all we know is that the SA filter has no ADBV (anti drainback valve).

On the aftermarket side; there is a split with some using a new PN and some calling for the existing PN. And there is some specs available on these (thank you Wix and Rock Auto).The key differences shown by Wix comparing a 1995 MX6 to a 16 SA filter is the bypass setting and the height.
The bypass valve for 2016 is between 37 & 75% greater, and the height for 1995 is 20% higher.
Both filters have specs stating there is less than a 2psi drop at 4gpm.

If all else is equal with the internals...
The 20% difference equates to 20% more volume and area.
In hydrodynamics, smooth flow pressure drop is inversely proportional to pipe size. In a turbulent environment, however, it is inversely square- so that 20% increase in volume quickly becomes a 44% reduction in pressure drop.

But all else being equal is not the case...
The ADBV is going to generate some turbulence; but the pressure drop on a clean filter has the same specs, so does not appear to be a concern.

Then there is viscosity; changes are proportional here as well, thicker oil will have a higher pressure drop.
When the old filter spec (whatever it was) was created, we were commonly using 10w30 (at least in the states). Now we are using 0w20.
Could you explain more about pressure (drop?) in accordance to oil weight?
 

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Discussion Starter #3
Could you explain more about pressure (drop?) in accordance to oil weight?
Pressure drop across a system is the result of friction; which correlates to resistance of flow. Resistance in a straight system is mostly volume and viscosity; once you start introducing imperfections then those factors are compounded.

Why? I believe this all goes back to Isaac Newton and the Laws of Motion; going through the mazes in an oil filter means a lot of changes in directions; it requires potential energy to overcome the kinetic energy of straight flowing oil. And the amount of energy is dependant on the viscosity... and it goes on

Google should have plenty of reading material if you search for Pressure Drop Viscosity
 
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Pressure drop across a system is the result of friction; which correlates to resistance of flow. Resistance in a straight system is mostly volume and viscosity; once you start introducing imperfections then those factors are compounded.

Why? I believe this all goes back to Isaac Newton and the Laws of Motion; going through the mazes in an oil filter means a lot of changes in directions; it requires potential energy to overcome the kinetic energy of straight flowing oil. And the amount of energy is dependant on the viscosity... and it goes on

Google should have plenty of reading material if you search for Pressure Drop Viscosity
- So basically, newer specification oil filters have become smaller in size in order to account for less pressure drop occurrence during 0w20 application? ... It would be incredibly useful if newer cars had oil pressure gauges.

- Is it best to avoid the SA filter without ADBV?

- In terms of viscosity in proportion to pressure drop percentage, which oil viscosity do you recommend on average? Does the skyactiv oil filter design impose limitations on an engine which otherwise features tolerances suitable for up to 10W50 oil? Weights such as 10W30, 10W40 are commonly used with Skyactiv engines in places such as Australia.
 
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Bottom line, never use Fram anything.
Agreed once again. On the contrary, Mann is a highly excellent OEM oil filter maker for the German brands. In general, German OEM stuff such as brake rotors, pads, oil filters, etc are very good quality. Luckily some of this stuff can be found for our cars as well, which is great.
 

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Discussion Starter #7
- So basically, newer specification oil filters have become smaller in size in order to account for less pressure drop occurrence during 0w20 application? ... It would be incredibly useful if newer cars had oil pressure gauges.

- Is it best to avoid the SA filter without ADBV?

- In terms of viscosity in proportion to pressure drop percentage, which oil viscosity do you recommend on average? Does the skyactiv oil filter design impose limitations on an engine which otherwise features tolerances suitable for up to 10W50 oil? Weights such as 10W30, 10W40 are commonly used with Skyactiv engines in places such as Australia.
While I do not know why they shrunk the oil filter, "accounting for less pressure drop" is highly doubtful; there are much more plausible reasons like airflow through the engine compartment and associated cooling... and lower overall cost for the filter and the oil.

ADBV- there does not appear to be any consequences in having one when not required.

As for US vs the world recommendations; there are more differences than oil viscosity, the non-American version of the engine has different hardware and software for the higher compression and different fuel blends. I am not going to research or give recommendations on using something that differs from OEM without knowing what is all at play.
 
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While I do not know why they shrunk the oil filter, "accounting for less pressure drop" is highly doubtful; there are much more plausible reasons like airflow through the engine compartment and associated cooling... and lower overall cost for the filter and the oil.

ADBV- there does not appear to be any consequences in having one when not required.

As for US vs the world recommendations; there are more differences than oil viscosity, the non-American version of the engine has different hardware and software for the higher compression and different fuel blends. I am not going to research or give recommendations on using something that differs from OEM without knowing what is all at play.
So this got me thinking, theoretically speaking, as long as you continually change the oil filter enough to keep the oil from becoming contaminated, and you add some sort of oil additive/detergent package into your crankcase regularly wouldn't you be able to get significantly more life from an oil interval?

Do you have an opinion on racing oriented oils such as Motul or Redline? My experience with Motul has left me convinced that its worth every penny of the extra asking price. No matter how dirty or used up the oil was, I swear it just continued to protect the internals - particularly the cylinder head as if it was still new oil PAST the recommended oil interval. After merely a few thousand miles using almost any other oil during cold starts my BMW's cylinder head would be making a racket until oil came up to temp along with infamous lifter tick. Fresh oil stopped this, but not nearly as long...

I also really liked Shell rotella, especially for the price. I only used it once because I noticed some build-up on the camshafts when peeking inside the oil filler neck... and .. well.. that Diesel oil sure did seem to do it's job when I pulled out the oil filter. the stuff flows very well during cold starts, oil temp gauge indicated quicker warm ups, but it maintained consistently 10 celcius lower oil temps for 5000 miles straight when compared to typical Castrol... Good stuff. This straight 6 made it really easy to compare oils for some reason, especially since it has an oil temp gauge.
 

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Discussion Starter #11
...as long as you continually change the oil filter enough to keep the oil from becoming contaminated, and you add some sort of oil additive/detergent package into your crankcase regularly wouldn't you be able to get significantly more life from an oil interval?
Amsoil kills Motul and Redline. Especially when frozen.
Kind of straying off-topic now, aren't we?

Changing the oil filter really is only removing the particle contamination from the system; and does not account for the chemical contamination, either direct (fuel, water, antifreeze) or indirect (oxides and acids formed within the oil).

Topping off with some additives may seem like a good idea; however, without knowing the exact chemistry of the original additives and their condition, you could be making the chemical contamination worse

So you notice cooler oil and some deposits when you use Diesel rated oils... Enough reason not to use them in my opinion. What are the designed-for temperatureS (engine, oil, coolant)? The trend for the last few decades is engineering toward higher oil temperatures and cooler coolant, could you be misinterpreting the results as being a good thing?
 

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So this got me thinking, theoretically speaking, as long as you continually change the filter...
...racing oriented oils such as Motul or Redline? My experience with Motul has left me convinced that its worth every penny of the extra asking price. No matter how dirty or used up the oil was, I swear it just continued to protect the internals - particularly the cylinder head as if it was still new oil PAST the recommended oil interval.
There’s an interesting macro data analysis article HERE that touches on these areas, and to stick to the thread topic, the article directly addresses oil filter impact on UOA results. There is room to argue with the article on at least a couple fronts, but so far as the analysis itself it is a solid analysis of the data evaluated.
 
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Kind of straying off-topic now, aren't we?

Changing the oil filter really is only removing the particle contamination from the system; and does not account for the chemical contamination, either direct (fuel, water, antifreeze) or indirect (oxides and acids formed within the oil).

Topping off with some additives may seem like a good idea; however, without knowing the exact chemistry of the original additives and their condition, you could be making the chemical contamination worse

So you notice cooler oil and some deposits when you use Diesel rated oils... Enough reason not to use them in my opinion. What are the designed-for temperatureS (engine, oil, coolant)? The trend for the last few decades is engineering toward higher oil temperatures and cooler coolant, could you be misinterpreting the results as being a good thing?
The difference was not major. Whenever I change the oil, regardless of what I am using the oil temperature will be a little bit lower until it's almost time to change again. It's not a bad thing because BMW's oil temps tend to be sky high, so anything short of reprogramming the electric water pump to maintain more reasonable temperatures within the engine is going to be beneficial.

The oil filter on these cars is not inside a metal container, so when I did look at it, it was all gunked up and filthy. After running shell rotella for an oil interval the next oil filter came out exponentially cleaner. If your crankcase is really gunked up I don't see anything wrong with using diesel oil ONCE.

FWIW, I used to have a MK4 Volkswagen Golf with the gasoline 2.0 engine. Mechanic recommended I used 15w40 diesel oil; and it's exactly what i ended up doing for a couple oil intervals. This older engine seemed to absolutely molest the engine oil supply with fuel - it smelled putrid even when the oil was still clean. I was changing the oil every 1500-2000KM on that car and it was coming out absolutely filthy... Even in this case, it seems like all those diesel additives can only do so much for such a filthy fuel diluting motor. Anyhow - I've never used shell rotella in my Mazda and likely never will. I went back to using typical gasoline oils with my BMW afterwards and didn't look back.

As for oil additives, alot of them claim that they are compatible with any sort of engine oil, so generally speaking, as long as you are using a good oil blend, and then adding good additives to the oil supply later on, I think it would be beneficial for the engine. There is this stuff called Liqui-moly Ceratec, and then STP Synthetic oil treatment which I thought was good stuff. I think it's worth a shot.

Amsoil kills Motul and Redline. Especially when frozen.
AMSoil is good, but not better than those two. In terms of cold flow it doesn't get much better than Motul one way or another. To claim that AMSoil is better simply because it flows cold when frozen is absurd. Yes cold flow is important, but you're making it sound like engine oil spends its life in freezing temperatures day in and day out, year round.

Quite frankly, Unless you are using 20W50 oil and park your car outside in the middle of a freezing winter, you don't have much to worry about unless you're the type to sit around letting your car uselessly idle. Aren't you concerned about how your engine oil performs at, you know? 100C operating temp? Because this is where Redline and Motul will run circles over anything else available on the market.

IMO, claiming that ANY 5W40 oil inhibits cold start flow to a degree where you can expect engine damage is completely absurd.
 

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Filtration is very important. I live in America and unfortunately "science" is currently out of fashion as a method for verifying facts here. I still adhere to its principles of standardized methods for data gathering and have made a career based on it.
In another profession I used both SAE and EPA standard tests to verify materials performance. As a result I have used the independent results published by Russ Knize using SAE J1858 and SAE J806 methods.
Mr. Knize's results can be seen here.
Good Luck and happy motoring.
 

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The higher oil temps is more of a side effect as a result of emissions. The issue is "dead zones" in the combustion chamber, one of which is the space between the top compression ring and the top of the piston. Minimizing that space is important to reducing emissions, but the closer to the fire deck the top ring is the hotter it runs and thus the hotter the oil runs that is on the cylinder wall that keeps the ring and bore from destroying each other. One of the reasons tolerances have been forced tighter is that the closer to the fire deck that ring is tighter the tolerances have to be to avoid the skirt slapping against the cylinder wall -- so as manufacturing has improved the ability to reduce that dead zone has improved as well.

This is where most of the sludging issue was eventually traced to with a multitude of engines and it's why in modern engines irrespective of what the manufacturer allows using a full-synthetic can be of benefit; their higher coking temperature (and not by a little either) can make quite a difference.

Some Audi gas engines are known for doing this if you run dino oils to a degree that their oil pump pickup screen gets blocked, and then you're hosed. They "recommend" (but do not require) full-synthetics..... you'll make it out of warranty if you don't run full synthetics in those, but beyond that, especially once you get into the 100k+ mile area, all bets are off.
 

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Discussion Starter #16
FWIW, I used to have a MK4 Volkswagen Golf with the gasoline 2.0 engine. Mechanic recommended I used 15w40 diesel oil; and it's exactly what i ended up doing for a couple oil intervals. This older engine seemed to absolutely molest the engine oil supply with fuel completely absurd.
Kind of irrelevant to the discussions on oil we have here; as VW recommended both 15/40 & 20/50 as acceptable if the temperature was above -10C
 
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The higher oil temps is more of a side effect as a result of emissions. The issue is "dead zones" in the combustion chamber, one of which is the space between the top compression ring and the top of the piston. Minimizing that space is important to reducing emissions, but the closer to the fire deck the top ring is the hotter it runs and thus the hotter the oil runs that is on the cylinder wall that keeps the ring and bore from destroying each other. One of the reasons tolerances have been forced tighter is that the closer to the fire deck that ring is tighter the tolerances have to be to avoid the skirt slapping against the cylinder wall -- so as manufacturing has improved the ability to reduce that dead zone has improved as well.

This is where most of the sludging issue was eventually traced to with a multitude of engines and it's why in modern engines irrespective of what the manufacturer allows using a full-synthetic can be of benefit; their higher coking temperature (and not by a little either) can make quite a difference.

Some Audi gas engines are known for doing this if you run dino oils to a degree that their oil pump pickup screen gets blocked, and then you're hosed. They "recommend" (but do not require) full-synthetics..... you'll make it out of warranty if you don't run full synthetics in those, but beyond that, especially once you get into the 100k+ mile area, all bets are off.
Interesting, well, it's also a factor of the plastic electric water pump which doesnt function in order to get temperatures up quickly; which is great, but once the oil does get up to temp, oil temp would stay at a hair below 120C unless it's cold outside in which case it tends to stay at around 95-100. bmw did it for a cleaner burn, but it absolutely destroys gaskets, seals, spark plugs, ignition coils, not to mention simply outrageous heat soak going on inside the engine bay. Plus I can only imagine what running an engine literally just short of full on overheating is doing to the engine oil. The Skyactiv engine, in contrast runs much cooler which becomes very apparent when you compare spark plugs from both engines side by side..
 
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Kind of irrelevant to the discussions on oil we have here; as VW recommended both 15/40 & 20/50 as acceptable if the temperature was above -10C
Sorry, dont mean to stray too far from your original topic.

To be honest... generally speaking I dont think engine tolerances vary much from model to model, meaning this recommendation probably can apply to MOST vehicles. Is it worth attempting to do so? Probably not. Most engines on the market are not a new design. The ones that are "new" are almost never a clean sheet design, but simply an evolution of previous technology. This means engine tolerances even these days are NOT as strict as everyone makes it seem where running anything but 0w20 will blow your motor.
 

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To be honest... generally speaking I dont think engine tolerances vary much from model to model, meaning this recommendation probably can apply to MOST vehicles.
The reason the VW allowing 15w40 as irrelevant is that the engine design is ancient- engineered before unleaded gas, catalytic convertors, or fuel economy were topics.
 
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The reason the VW allowing 15w40 as irrelevant is that the engine design is ancient- engineered before unleaded gas, catalytic convertors, or fuel economy were topics.
Yes that's true, but I think that in the case of our engine, even up to 10W50 should be totally acceptable unless you do not park in a garage during the winter. This engine, especially in comparison to many others I have operated; seems to fare exceptionally well during cold starts. I don't like to use 0w20 because the valvetrain clatter is too much for me, especially when starting from cold. I especially did not like the way it sounded with the hood up even once the engine was fully warmed up. With 5W40 all you can hear is the injectors ticking away.

Sorry - back to the topic of oil filters. What do you think of the Mann oil filter for the 2015 Mazda 6? Mann is a top-notch oil filter company. When comparing the filter element to other brands, clearly seems like better quality based on how intricate the filter element is. Now it's not a cheap filter so i'm not sure if it's worth upgrading over the typical Skyactiv filters, but the brand makes OEM filters for BMW as well as other german brands and I was exceedingly happy with previous applications.
 
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