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· Registered
2002 Forester L
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170 Posts
Discussion Starter · #1 ·
There appears to be 2 oil filters for Subaru in general, one slightly smaller (for Turbo?), and one larger. Thanks to wixfilters.com(which has a little more detailed spec available online), I spent some time digging for info, and found that physically they should fit either way, but the smaller version (51365) has SIGNIFICANTLY better specs than the other (Wix part 51365 and 51334).

Aside from the physical/size difference:

Wix 51365 Wix 51334
Beta Ratio 2/20=15/22 2/20=22/40
Burst Pressure-PSI 300 280

All other specs are exactly the same.

Here's the kicker, Wix51365 is fit as the transmission spin-on filter. I have posted a thread on the old site regarding subie/non-subie ATF filters and found that subie version has a cylinder screen/mesh that covers the bypass (no true bypass) comparing to the non-subie version.

I'll start using 51365 all around once my filter reserve is exhausted, maybe once or twice yearly for the tranny, and reasonable OCI for the engine.

Comments? (BTW, my Forester is out of warranty).
 

· The Modfather
2019 Impreza 5dr Sport - Manual
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8,209 Posts
I'm a little confused by your post. Are you saying you want to use a WIX oil filter on your ATF, in place of, the current spin one one? AFAIK this is a bad idea. Maybe HondaSlayer can chime in. There is no pressure / bypass valve in the ATF for a reasion I suspect. They list the ATF filter as a non service item. I'm not saying it will hurt to change it but with another ATF filter. Using an oil filter may not be such a good idea though.

I just picked up two 51334 filters but that's for my Subaru with the H6 motor. I've always liked wix myself.
 

· Registered
2002 Forester L
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170 Posts
Discussion Starter · #3 ·
I will use Wix 51365 for both my engine and ATF filters.

There's a bypass valve in the subie ATF filter. But the bypass goes into a mesh screen, instead of straight thru in an oil filter.
 

· Registered
1998 Forester "S" lifted. Bog-o-matic
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2,007 Posts
The AT Filter is a non replacement filter.

Exceptions are if the filter is damaged or has been removed and re-installed (will leak).

It won't hurt to replace it, but you are just throwing your money away.

Better to just change the fluid every 45k or so...
 

· Registered
2002 Forester L
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170 Posts
Discussion Starter · #5 ·
I already replaced the ATF filter once with non-subie version with no ill effects (actually felt better response from tranny. could be due to fluid drain/fill too). Since the aftermarket version is so much cheaper, I can do it more, and use only one filter type for everything.

The urban myth of people removing the wrong filter and destroy tranny is probably due to no oil in AT at all and overfill for the engine, not due to the filter mixup.
 

· Registered
1998 Forester "S" lifted. Bog-o-matic
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2,007 Posts
z00m said:
I already replaced the ATF filter once with non-subie version with no ill effects (actually felt better response from tranny. could be due to fluid drain/fill too). Since the aftermarket version is so much cheaper, I can do it more, and use only one filter type for everything.

The urban myth of people removing the wrong filter and destroy tranny is probably due to no oil in AT at all and overfill for the engine, not due to the filter mixup.

Urban myth?

I think not.

I do at least one transmission a month thanks to Jiffy Lube type places.

Myth Busted.
 

· Registered
2002 Forester L
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170 Posts
Discussion Starter · #7 ·
So what kind of damage have you see? I would think you couldn't go far with an empty sump on an auto. Drain the excess engine oil out, and refill ATF would probably do it. Or do you mean quickie lube places filled engine oil into the tranny?
 

· Premium Member
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261 Posts
I just changed my ATF and put a new filter OEM AT on. One look down the center tube told me it is much different than my engine oil filter. The AT filter, though smaller than the engine filter feels like it weights about 50% more. I don't know where the AT filter is in the hydralic circuit. If the filter is on the high pressure side it could see 150 + PSIG. The filter cost me $22 but, my AT will cost over 3,000 if I wreck it trying to save $20 using the wrong part. JMO Ed
 

· Registered
2002 Forester L
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170 Posts
Discussion Starter · #9 ·
I have cut open the OEM piece and found it's just an oil filter with the bypass opening covered in a fine mesh cylinder. Wix 51365 has a burst pressure of 300psi and the bypass opens around 10psi and a flow rate of around 10 gallons a minute (and Wix claims that this is the filter meets the OEM ATF filter spec). I can image that the OEM version can be clogged since there's no true bypass.

I'm not really trying to save anything since I plan to change it more often. I saw a very small amount of fine metal dust still gathered on the drain plug when I did the first drain/fill, and prompted me to think that the OEM filter should do a better job. Did you notice any metalic sludge on your drain plug?
 

· Premium Member
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261 Posts
You may be onto something zOOm but, I don't know about the media etc. For me it's too late to reconsider as I just put a Subaru OEM AT filter on and my next change is due at 200,000 miles. Subaru says no need to change, except for damage or rebuild but, being conservative I changed it at 100,000 miles anyway. I have changed my AT fluid(pan drain) every 30,000 miles and really didn't notice anything significate on the drain plug and I do look for this kind of stuff.
 

· Premium Member
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261 Posts
I seem to remember that AUTOZONE has an AT filter listed for the Subaru 4EAT. It was sold/made by Beck-Arnley and I knew nothing of that company except in the 60s they made clutches, throughout bearing and stuff like that. You may wish to investigate this as their price was ~$12 and would need to be ordered. Ed
 

· Registered
2002 Forester L
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170 Posts
Discussion Starter · #12 ·
The key probably is your frequent drain/fill. I got mine used, so don't know if it was ever serviced. Probably at least once since the parking rod was recalled and that needed a pan drop (Dealers don't put old fluid back, do they? And they clean magnets while at it?).

I plan on drain/fill more frequently, maybe every 12k or so. 8 qts of ATF a year is really cheap insurance (consider the gas price!). When my magnetic drain plug is super clean, it'll reduce my urge to change the filter :)
 
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