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1996 OBW 2.5 Auto
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Discussion Starter #1
Question: Anybody ever hear of or subscribe to the opinion that only OEM Oil Filters should be utilized? I ask because when I took my first car to a shop many years ago (a '79 Toyota), the mechanic, who was a very well respected master mechanic who took pride in getting the maximum life out of vehicles for his cutomers, insisted on only using OEM filters. He provided what I only remember as being a very solid reason for doing so, but I cant recall exactly what his theory was.

I believe he said that the OEM filters, while similar in filtration ability as after market filters, somehow created or maintained the exact oil pressure required for the specific engine, unlike after market filters, which are designed for usage on so many different vehicles.

I recalled this because on a recent posting on this site, someone recommended a link to a Subaru only engine re-builder. In reviewing that site and investigating the warranty that the re-builder provides on his engines, he specifies that to keep the warranty in effect, only OEM oil filters can be used.

Anybody know the theory behind this?
 

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'00OBW, '96&'94 Legacy - all rusted RIP, current: 2016 Focus MT
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Subaru and most other automakers just pick a vendor such as Purolator or Bosch or whoever and put the manufacturer's name on the filter. The manuf might give them specs to have the filter made. Subaru switched vendors in recent years I forget who is making the Subaru oil filters now. There was also an issue some time back with the gasket leaking on some of them I think.

Anyway I don't think you could go wrong with a quality aftermarket filter such as Wix (aka napa gold) or some others. Who has that link to where someone cut open various filters to see how well they were made. Some cheaper filters use cardboard and other junk in them that might not hold up well.

The requirement to use genuine Subaru filters by that rebuilder might be that the genuine filter is at least pretty good quality, whereas something from the dollar store might not be so good. Some people like to avoid what is sometimes called the orange can 'o death.

Could also be the genuine filter's bypass valve is like 24 psid I think, whereas many aftermarkets it is much lower say 9 psid.
 

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'00OBW, '96&'94 Legacy - all rusted RIP, current: 2016 Focus MT
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That site I was thinking of had pics of a bunch of filters cut open. It was a few years old maybe there's an updated study now since manuf's may have changed some things over the years.

Here's a filter I cut open last year
 

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06 OBW 2.5, 05 Forester, had 03 H6 OBW
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Any filter built to the right specs and of quality construction will provide as long an engine life as the OEM filter- trick is to find such.

Take FRAM for example- cheap crap!


Dave
 

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04 Outback H6
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One site I found useful that was a bit more recent was:

http://home.mindspring.com/~ed_white/id7.html

The additional links on the bottom of the page are great in helping you decide which filters to use.

In Canada we don't have many retailers who sell Purolator filters, and I can get the Denso filters cheaper than the "six star" value branded filters from the dealer. The bonus is that the Denso filter also fits my wifes car so I only need to buy 1 filter and stock up on them.
 

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2012 Forester Limited, 1973 MG Midget
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I have always used Bosch filters. I know it's not necessary, but I still do 3000 mile oil changes on conventional oil, and the oil always comes out clean, so I've never switched filter brands.
 

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2008 Outback 2.5
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porcupine73 said:
That site I was thinking of had pics of a bunch of filters cut open. It was a few years old maybe there's an updated study now since manuf's may have changed some things over the years.
Is this the site?

http://www.knizefamily.net/minimopar/oilfilters/index.html

Here is the thread I found it from while reading about filters last year:

http://www.subaruoutback.org/forums/showthread.php?s=&threadid=12623

I read a bunch of oil threads and came to these conclusions:

Filters:
Fram which used to claim to be the best are now probably the worst. Some have actually had disintegration of internals found when changing filters.

Wal Mart SuperTech or Autozone filters are the least expensive but nearly the highest quailty.

Oil:
Any properly SAE rated oil is fine. For turbo models, there is a little more criticality in choosing oil.
Synthetics oil molecules are more uniform than conventional oil and are therefore a better choice for turbo applications.
Changing the oil and filter regularly at 5000 miles is more critical than the type of oil you use (short trip drivers should change at least this often, long trip drivers can safely go farther).

Personal Experience:
Changing the Oil regularly is the cheapest insurance for keeping your engine running. I have always changed my own oil 2-4 times a year and have never had an engine problem related to oil except once when the oil pump died on my 4Runner and the oil pressure idiot light was dead :eek: .
 

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2018 328d Wagon / 2018 3.6R Touring
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CNY_Dave said:
Any filter built to the right specs and of quality construction will provide as long an engine life as the OEM filter- trick is to find such.

Take FRAM for example- cheap crap!


Dave
Especially re-assuring as I think the new "Blue" filters from Subaru are manufactured for Subaru by Fram.
 

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06 OBW 2.5, 05 Forester, had 03 H6 OBW
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lfdal said:


Especially re-assuring as I think the new "Blue" filters from Subaru are manufactured for Subaru by Fram.
Yeah, I'm waiting for them to show up at my dealer.

I will dissect my last black filter and upon removel my 1st blue filter, and compare, and maybe slap the whole mess on the parts counter if the new one is crap.


Dave
 

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There are several threads on the SubaruForester.org forum about the SOA oem filters having changed from the Japanese-made to ones made by a North American manufacturer, presumed to be Honeywell, which also makes the Fram products.

Getting past the issue of Fram history and design, and the fact that the new oem filter internal construction appears visually the same as Frams, the discussion recently turned to the internal pressure relief valve. Apparently, research by some posters suggests that Subaru requires the relief valve to function in the range of 23 psi, whereas many aftermarket filters that will fit Subarus typically have valves that are designed to release at far lower pressures. The thought is that the aftermarket products are made to be applicable to a variety of cars, mainly based on their volume and attaching dimensions, whereas the filters made specifically for Subaru to its specs would have the required higher release pressure.

Whether the difference is critical does not appear to have been resolved, but obviously, the original posters' sources think it is important enough, for this reason or another, to specify using oem.
 

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1996 OBW 2.5 Auto
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Discussion Starter #13
Thanks OM, you have vindicated my memory from 30 years back. As I said in the original post, I remember the primary reason for only OEM filters being something to do with oil pressure specs of some sort. Your info confirms that, thank you.
 

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07 2.5i
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779 Posts
There's a huge thread on Subaru oil filter bypass pressure requirements on BITOG.
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1410171&gonew=1#UNREAD

Basically, the FSM calls for 23 psi for the bypass valve, and Subaru oil pumps flow unusually high volume. And it seems none of the aftermarket filters meet the bypass valve psi requirements. Lots of big ego debating on that thread, and stuff I don't understand, so I'm not sure what to make of it.
 

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2005 Outback H6 3.0 LL Bean
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So the idea is that a Subaru oil pump generates an unusually high pressure at the filter, causing filters with low bypass pressures to mistakenly go into bypass, not filtering any oil?

That would be bad...if it's true.

Time to read the rest of the BITOG thread and try to cut through the BS.

EDIT: Wow, that thread is a little bit of useful information wrapped in 15 pages of p*$$**g match. Not a recommended read.

I have to admit, though, that my next oil filter will not be a Wix that fits every engine under the sun. It will be a Purolator, AC Delco, or Bosch that is Subaru-specific.
 

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1997 SVX Bordeaux 2012 OBW 6 speed 1992 SVX Ebony 1992 SVX Claret
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Walmart Supertech for me, they're around $2-3.00 for each of my vehicles and have great specs and reviews.
 

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1997 outback limited. 295,000 miles and counting
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All i can tell you is that i have 206,000 miles on the orginal motor and I've been using wix(car quest) filters and changing my oil every 5,000. Since the motor is stilling going strong, I'm going to keep doing what i'm doing.
 

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2005 Outback H6 3.0 LL Bean
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Blacky - Do you have a link for specs on SuperTech filters? I couldn't find anything online. Are they printed on the packaging?

Sario - I understand what you're saying. My engineering side just won't let me buy the filter with the low-pressure bypass now that I've read up on the differences. The argument for a filter with a higher bypass pressure makes sense to me.
 

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1997 outback limited. 295,000 miles and counting
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obsolete said:
....... My engineering side just won't let me buy the filter with the low-pressure bypass now that I've read up on the differences. The argument for a filter with a higher bypass pressure makes sense to me.
I can see why people would go only OEM, especially when it's only another coupe dollars to buy the subaru one. better than safe than sorry i guess. I would probably even jump on board with you, if i didn't really dislike my local dealership so much.

But I dont think with the amount off surface area in the filter the bypass is going to be pushed open untill higher RPMS. I toyed with idea of tapping the oil filter, and using a gage from work to test the pressure it. But i'm really not sure that would prove anything, I'm hardly and engineer. Plus i have to many half started projects around the house as it is
 

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07 2.5i
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Sario said:


I can see why people would go only OEM, especially when it's only another coupe dollars to buy the subaru one. better than safe than sorry i guess. I would probably even jump on board with you, if i didn't really dislike my local dealership so much.

Order case lots from one of the dealers that sell parts online. Cheaper, they show up at your door, and you'll be set for a while.
 
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