WIX 57055 filter vs. Subaru Oil Pump/Filter Compatibility Analysis: Please help me make this correct!

rnsc

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This is not correct - the oil filter is just a small "resistor" in the oiling system. The PD oil pump doesn't care is there if there's a bypass valve in the oil filter or not ... it makes no difference to the PD pump.
Agreed. The PD pump will move the amount of oil through the gears based on RPM regardless of ... anything, including the oil filter behavior. But "Anything" includes the pump bypass relief valves, which can open, in which case the oil does not go through the engine.
There will be a max pressure and volume flowing in the gallery before the oil filter when the oil pump is in pressure relief.
Forgive my not being certain of terminology, but I assume that "gallery" means the engine? Not if something is stopping it from flowing that way - If something is stopping it, then the pressure will rise to open the pump first stage relief valve and eventually the full pump bypass relief valves, and the PD pump will be happy because it will be moving the oil that it must to rotate, just not through the engine. THIS is the sticking point: Does the WIX specification that says that the maximum flow is 8-10 GPM mean that due to the physics of oil fluid flow through the media mean that the pressure required rises very quickly and no-way can you force more than 8-10 GPM through the filter media? This would mean that the pump pressure relief values will open and the excess flow will simply bypass the filter AND engine. OR, does it mean that this is the design limit for the filter due to many unspecified factors such as rupture of the media, bending of the media support, failure of the media anchoring at the ends, etc. Hardly a good situation either. Either way WIX is saying that the 57055 is not suitable for an application which requires more than 8-10 GPM to flow, certainly not an FB25 whose PD pump HAS to move 58.1 qt (14.5 gallons) of oil per minute at 6000 RPM. UNLESS the failure mode is that the 57055 flow is limited as opposed to that the 57055 tears itself apart, AND it is OK if the engine only gets 40 quarts , which violates the understanding that oil flow is proportional to RPM (Unless the pump is pumping at least 40% more than is needed at low RPM).
That volume will go through the filter and into the oiling system.
IF the filter will allow that volume to flow through it. But see above: WIX states "Max Flow Rate 8-10 GPM". I take this to mean that manufacturing variations result in the Max Flow Rate limit varying from filter to filter to be between 8 and 10 GPM. An FP25 would pump 10 GPM at (40/58.1)*6000 = 4100 RPM, and 8 GPM (Presumably a rate that their design is certain to support) at 3300 RPM. Have you ever exceeded 3300 RPM? I have, likely every time I go out. 4100 RPM? I have too. I have even exceeded 3300 RPM for an extended period of time! Either (1) The filter will not allow this flow rate and the flow rate will be forced to be lower, the pressure will rise, and the pump bypass relief valve will open at 21 PSI and a little higher the filter bypass valve will open at 23 (or 27) PSI, or the filter will mechanically fail (tear apart). I think the likely result is that the bypass valves will open, the engine will get less oil, and the oil it gets will be dirty. According to the WIX specifications for the 57055, that filter is simply not suitable for use on an FB25 if the engine is run over 3300 RPM. (To be clear, I am hoping that someone will point out a flaw in my reasoning, not that I will succeed in shooting down WIX).
The bypass valve on the filter only operates from the delta-p across the filter.
Clearly.
So if that volume going into the filter (along with the viscosity of the oil factor) causes the filter to bypass, that same total volume will still be going through the filter.
Yes, but it will not all be filtered, some fraction of it will be dirty, very dirty. Which IS better than no oil at all, but certainly not a desirable situation.
Only some will be bypassing the media.
Oops, yes, sort of like a bypass oil filter, except that the bypassing oil is washing over all of the stuff that the filter has previously filtered out, washing it back into the engine, where as with a bypass oil filter the flow is split upstream of the filter so that the oil that bypasses goes out no dirtier than it came in. You might as well have no filter at all if this happens frequently.
The PD oil pump's pressure relief valve operates separately and disconnected from the bypass valve in the oil filter.
Yes, and it opens about 2 PSI earlier than the Subaru filter, 6 PSI sooner than the WIX filter, stealing some of that Positive Displacement flow such that the engine does not get a flow of oil that is proportional to the RPM. Was it overkill so that this is OK? Or is it important at high RPM to have that much oil?
 

rnsc

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You will never know, and never be able to "calculate" what's going on unless you actually know the delta-p vs flow curve of the specific oil filter you're looking at. The only way to really know that is a controlled lab test by a lab capable of doing such a test. The graph below is for a Purolator PureOne with hot oil (approx 5W-30 at 200 F). It was done by Purolator in their test lab.
Yes, but this is great, thank you. It says that it is more or less linear. For an example synthetic blend media. Of course this could be alot worse/different for cellulose etc.
In this case, you can see that at 12 GPM of flow, the delta-p across the oil filter is only 5 PSI. If the bypass valve was set to 15 PSI, then at 12 GPM with the hot oil the bypass would be far from opening.
Yes, specifically at 14 GPM.
Keep in mind that filter bypass valves are set for worse case conditions over an expected OCI. That includes cold oil operation, max RPM at times, pressure spikes and also some headroom for media loading with debris, which increases the delta-p across the filter with use.
Too bad we don't have a curve for that.
If you're worried about the a filter bypassing too much on a high pump flowing Subaru, then use filters with the high bypass setting specified for Subarus.
Yes but they are also "Enhanced Cellulose". PureOne does not give a micron rating.

They all seem to leave out some information, and most of them leave out all information.
 

rnsc

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The oil pump has a two-stage bypass, and the first stage is at 21.7psi. Yet the fsm is saying it's 40 psi at 600rpm(idle)..? The first stage is always bypassing?
Yes, it clearly says that. Note that this is bypassing within the pump, meaning that the engine is getting less oil. We have no handle on how much oil that is since it is clearly a restricted bypass otherwise the pressure would never rise above 21 PSI external to the pump. But at least the oil that is flowing is flowing through the filter.
 
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Yes, it clearly says that. Note that this is bypassing within the pump, meaning that the engine is getting less oil. We have no handle on how much oil that is since it is clearly a restricted bypass otherwise the pressure would never rise above 21 PSI external to the pump. But at least the oil that is flowing is flowing through the filter.
Maybe Trav can add some insight since he’s added quite a bit of knowledge about Subarus from his experience. However, it feels like you’re really overthinking this because 1. There’s millions of these engines operating with a wide gamut of filters, including ones of more questionable quality than Wix even considering some of the quality issues of late; and 2. If there had been failures attributable to the filter M&H would likely have made changes by now or removed that filter from the Subaru application list.

If there’s one thing to watch on FB filters IMO paraphrasing from ZeeOSix, it’s to avoid filters with thread-end bypasses due to the inverted nature of the mount. Dome-end would be preferred because at least then any particulate will have to flow past the media prior to reaching the bypass, where a thread-end could theoretically fail and allow a path straight from the dirty side into the clean side if the bypass failed or opened.

That said, the 7055 used to be thread-end bypass but I believe there have been pics that the newer ones have changed to dome-end and have a larger element than the original version.
 

rnsc

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I am not exactly sure if I actually understand your post . Are you referring to the oil filter bypass ?
Yes, but note that this is one of two senarios of what might be happening. (1) seems more reasonable and likely, especially or at least in the case of a synthetic blend PureOne filter per ZeeOSix's graph.
The oil filter bypass valve will allow the oil to bypass the filter when using your numbers when the differential pressure is 23.2 .
But per ZeeOSix's graph the differential will never reach 23.2 unless it is clogged, at least with synthetic blend, at least with PureOne synthetic blend. I/We don't have such a graph for any other kind of media or any other brand, such as WIX' Enhanced Cellulose, or Subaru's who-knows what. So we can assume that it is something similar, but that is probably a poor assumption. Synthetic media is sold as something that does a better job of filtering even as the oil flows through it easier, so however it looks, it is very likely that higher pressures are involved. How much, or if it is linear-like, we don't know at this point.
With the engine running the by pass valve will open when the pressure on the unfiltered side of the element has a 23.2 psi differential of pressure as compared to the filtered side of the element. The oil pump and oil filter bypass do two different things.
Yes, I understand that.
Push the easy button in this instance and use the oem or a proper rated filter.
So I would like to use a 20 micron filter, 99%+. Some brands talk about these, most don't. The rest of the "ratings" almost nobody provides any information, except WIX, and what they provide contradicts the engine specifications, per this thread. My hope is that someone who understands these things better can provide some information to improve clarity. Many many companies well products that are all hype and we buy them naively. We will never know if our car would have gone 300,000 miles instead of 150 if we had used a different filter. It wore out, as expected. I am trying to make an intelligent choice based on facts and understanding, not trust in the care salesman.
 

rnsc

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Yes, but note that this is one of two senarios of what might be happening. (1) seems more reasonable and likely, especially or at least in the case of a synthetic blend PureOne filter per ZeeOSix's graph.

But per ZeeOSix's graph the differential will never reach 23.2 unless it is clogged, at least with synthetic blend, at least with PureOne synthetic blend. I/We don't have such a graph for any other kind of media or any other brand, such as WIX' Enhanced Cellulose, or Subaru's who-knows what. So we can assume that it is something similar, but that is probably a poor assumption. Synthetic media is sold as something that does a better job of filtering even as the oil flows through it easier, so however it looks, it is very likely that higher pressures are involved. How much, or if it is linear-like, we don't know at this point.

Yes, I understand that.

So I would like to use a 20 micron filter, 99%+. Some brands talk about these, most don't. The rest of the "ratings" almost nobody provides any information, except WIX, and what they provide contradicts the engine specifications, per this thread. My hope is that someone who understands these things better can provide some information to improve clarity. Many many companies well products that are all hype and we buy them naively. We will never know if our car would have gone 300,000 miles instead of 150 if we had used a different filter. It wore out, as expected. I am trying to make an intelligent choice based on facts and understanding, not trust in the care salesman.
Oh, so I would like to use a properly rated filter. What is properly rated? The car manufacturers only say to buy theirs, and don't tell us their ratings for anything, even though there are clearly better products. And if I knew, how could I judge the filters on the market against the enumerated proper ratings? They sell on hype, not facts or ratings. But alot of people out there know something. So I am trying to aggregate it. At least to have something better than a bunch of fear, uncertainty, and doubt on one side and blind trust and warm fuzzies on the other.
 

rnsc

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Yes, the stating of "Max Flow = 8 to10 GPM" by WIX and other filter makers is a big nebulous mystery on what that "spec" is based on.

All you could do is email or call WIX Tech Support and ask them what it means. It would only mean something if they told you what the delta-p is with a certain oil viscosity at the 8 to 10 GPM flow rate, similar to the data points shown in the graph in post #4.

If I had to make a guess on what it means, it could mean the filter is close to hitting the bypass valve setting at that flow rate, but again you don't know what the viscosity of the oil is at that flow rate, which is a big factor in the delta-p produced across an oil filter. Takes a lot less flow of cold thick oil to hit filter bypass than it takes with thin hot oil. That's why engines shouldn't be revved real high until after the oil has got to near operating temperature.
 

rnsc

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This alarmism on subaru filter bypass settings has been going on for decades. In the 4 subarus I have owned since 2008 I have maybe installed half dozen subaru filters. I have had no problems and have never seen a docunted oil problem attributed to the lower bypass settings on aftermarket filters.
How would anybody know if the engine wore faster than necessary, or typical due to inappropriate oil filter parameters? The engine wore out, you bought a new one.
 

rnsc

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No way to really know without an ISO 4548-12 efficiency test - just speculation without proof. Subaru may specify Fram to make the media different than the Fram filters.
Yes, it is a glaring error to assume that just because something is made by the same company, even in the same factory, even looks the same, that it is the same. Time is money, so is material. Cheaper filter material may look the same. Or, it could be the same too! One has to wonder why oil filter manufacturers do not publish specifications for their filters in general. If they are good filters, why would they be vague and evasive as to their specifications? Only one reason: They cut corners and don't want to advertise that.
 

rnsc

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Maybe Trav can add some insight since he’s added quite a bit of knowledge about Subarus from his experience. However, it feels like you’re really overthinking this because 1. There’s millions of these engines operating with a wide gamut of filters, including ones of more questionable quality than Wix even considering some of the quality issues of late; and 2. If there had been failures attributable to the filter M&H would likely have made changes by now or removed that filter from the Subaru application list.

If there’s one thing to watch on FB filters IMO paraphrasing from ZeeOSix, it’s to avoid filters with thread-end bypasses due to the inverted nature of the mount. Dome-end would be preferred because at least then any particulate will have to flow past the media prior to reaching the bypass, where a thread-end could theoretically fail and allow a path straight from the dirty side into the clean side if the bypass failed or opened.

That said, the 7055 used to be thread-end bypass but I believe there have been pics that the newer ones have changed to dome-end and have a larger element than the original version.
Thanks for the additional insight and heads-up.
 

rnsc

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Yes, the stating of "Max Flow = 8 to10 GPM" by WIX and other filter makers is a big nebulous mystery on what that "spec" is based on.

All you could do is email or call WIX Tech Support and ask them what it means.
I sent a message on their contact form (There is no email address or phone number). They did not respond either time.
It would only mean something if they told you what the delta-p is with a certain oil viscosity at the 8 to 10 GPM flow rate, similar to the data points shown in the graph in post #4.
Yep, or just a graph of delta-p vs. flow rate. That might get us to the 90+% level on this.
If I had to make a guess on what it means, it could mean the filter is close to hitting the bypass valve setting at that flow rate, but again you don't know what the viscosity of the oil is at that flow rate, which is a big factor in the delta-p produced across an oil filter. Takes a lot less flow of cold thick oil to hit filter bypass than it takes with thin hot oil. That's why engines shouldn't be revved real high until after the oil has got to near operating temperature.
Yes, very very much so. But who wants to sit there for 10 or 15 minutes when it is 0 F out? Pay me now or pay me later...
 

rnsc

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The 5/7055 filter is specified for 27psi bypass, which meets the requirements for bypass pressure required by Subaru for the FB25.
Subaru specifies 23.2 in the 2016 Outback service manual for the FB25. Is there a different piece of literature that specifies 27 PSI?
 

ZeeOSix

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Yes, and it opens about 2 PSI earlier than the Subaru filter, 6 PSI sooner than the WIX filter, stealing some of that Positive Displacement flow such that the engine does not get a flow of oil that is proportional to the RPM. Was it overkill so that this is OK? Or is it important at high RPM to have that much oil?
The oil pump's pressure relief doesn't open at 33 PSI (27 of the WIX bypass + 6 PSI). You said this before in post #1:
Given that the pump's main relief valve opens at 82.6 PSI, the difference between the 23.2 PSI pressure drop of Subaru's filter which leaves 59.4 PSI to push oil through the engine and WIX' 27 PSI pressure drop which leaves 55.6 PSI to push oil through the engine in the most extreme condition is likely not significant.

Only time I would worry about the engine being "starved"of oil flow is if the filter was so clogged up that it hit bypass when the engine was at low revs. If the oil filter hit's pressure relief when the engine is at high revs, then there's going to still be quite a bit of oil flow going into the oiling system. The amount of volume that the oil pump shunts away from the oiling system becomes greater if the pump hits pressure relief at a pretty low RPM and the engine is still revved higher and higher from that point. Hint: Don't run engines at high RPM when the oil filter is clogged up, lol.

Anyway, like said before ... if anyone is worried about the filter bypass setting on a Subaru that calls for a high bypass setting, then run filters that are specifically matched to those Subaru engines.
 
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First, I apologize for apparently dropping off the face of the earth. (1) I ignorantly did not realize that the forum did not send a notification with each reply, and (2) Unexpected holiday goings-on distracted me until last night. Second, thank you for your considered comments. I was (and am) hoping to learn something new!

Regarding "past videos of blue filter tear-downs there does seem to be a lot of consensus that the blue OEM filters have FRAM toughguard media elements. Those are marketed as 99% efficiency at 20 microns.", this is good information if it is true, which sounds like it probably is (Except the part about not being available right now). Regarding oil, I use Amsoil changing between 6 and 7,000 miles, less than half of Amsoil's recommendation for severe service, so I think it is safe to assume that the oil properties have not significantly degraded.

Subaru's indirect recommendation of Champ and ProTec unfortunately falls flat because the WIX website does not list a ProTec filter in their selector for the FD25 engine (2016 Outback with FB25), and the Champ website has only a general flier with warm fuzzy words, and a Red Hat Linux Apache Test Page for their On-Line order facility where I had hoped to do a look-up. I will look again later.

Thanks again, I will keep processing the thread.

Regarding the ProTec. It's a Wix jobber filter (shop filter). Here's a recent article on some upgrades to them forthcoming: https://www.aftermarketnews.com/wix-upgrades-protec-oil-filter-line/

For your application all three of these are applicable from Wix:

ProTec is PXL57055
Wix 57055
Wix 57055XP

All three cross reference directly to the Subaru 15208AA15A for your engine.

If you haven't checked out rockauto.com before it's worth a look. You'll find many filter options there when you search under your year/make/model. I really wouldn't stress it too much. While you can't get the OEM filters at the dealership right now you can still find them in autopart stores or online. My local Autozone has them. They just charge a lot more than the dealer part's department.
 
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ZeeOSix

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Yes but they are also "Enhanced Cellulose". PureOne does not give a micron rating.
Purolator gives the efficiency % at micron size on their website for their oil filters ... unless they have changed it up recently. Gotta look at the very bottom of the webpage, last I checked.

Just checked. The Asterisks (*) info is at the bottom of the web page.


1669269869541.png


1669269829764.png
 
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Subaru specifies 23.2 in the 2016 Outback service manual for the FB25. Is there a different piece of literature that specifies 27 PSI?
27 > 23.2, and it’s been discussed several times in other threads that because the bypass is spring-controlled, there is actually a range of opening. The bypass will begin to open slightly at a lower pressure, but will be fully open by the listed psi.

If you look at some Frams the bypass is listed at 8-12 psi or similar, meaning they give you when the valve first begins to open, and when it is fully open.

I guess if there’s one “happy” fact here it’s that when the oil is cold and the bypass “may” open, it’s when the car has sat all night and any particulates have settled to the bottom of the pan and likely not be circulating much when the filter is most likely to see a high delta-P.
 

rnsc

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Maybe Trav can add some insight since he’s added quite a bit of knowledge about Subarus from his experience. However, it feels like you’re really overthinking this because 1. There’s millions of these engines operating with a wide gamut of filters, including ones of more questionable quality than Wix even considering some of the quality issues of late; and 2. If there had been failures attributable to the filter M&H would likely have made changes by now or removed that filter from the Subaru application list.

If there’s one thing to watch on FB filters IMO paraphrasing from ZeeOSix, it’s to avoid filters with thread-end bypasses due to the inverted nature of the mount. Dome-end would be preferred because at least then any particulate will have to flow past the media prior to reaching the bypass, where a thread-end could theoretically fail and allow a path straight from the dirty side into the clean side if the bypass failed or opened.

That said, the 7055 used to be thread-end bypass but I believe there have been pics that the newer ones have changed to dome-end and have a larger element than the

Regarding the ProTec. It's a Wix jobber filter (shop filter). Here's a recent article on some upgrades to them forthcoming: https://www.aftermarketnews.com/wix-upgrades-protec-oil-filter-line/

For your application all three of these are applicable from Wix:

ProTec is PXL57055
Wix 57055
Wix 57055XP

All three cross reference directly to the Subaru 15208AA15A for your engine.

If you haven't checked out rockauto.com before it's worth a look. You'll find many filter options there when you search under your year/make/model. I really wouldn't stress it too much. While you can't get the OEM filters at the dealership right now you can still find them in autopart stores or online. My local Autozone has them. They just charge a lot more than the dealer part's department.
Thank you for filling this hole.
 

rnsc

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I need to digest all of this. You all have certainly contributed to my understanding, though I don't think I have a silver bullet. I will summarize my conclusions in a week or so. In the mean time if anyone has any additional insights or comments please don't hesitate to send them on. Thank you!
 
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I need to digest all of this. You all have certainly contributed to my understanding, though I don't think I have a silver bullet. I will summarize my conclusions in a week or so. In the mean time if anyone has any additional insights or comments please don't hesitate to send them on. Thank you!
A lot of folks have gone in circles with this very thing especially regarding the Subaru oil bypass and flow rates. Ultimately I think you’ll be fine with whatever you decide. For myself my preference is OEM. If that’s unavailable or I’m feeling like grabbing something else I like the O’Reily’s MicroGard Select. Often a good deal with their oil+filter specials. Another consideration I don’t see often here are FULL filters. NAPA sells this brand. I haven’t tried them yet, but many folks running asian vehicles seem to like them.

Cheers!
 
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