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Do Subaru oil filters not have anti-drainback valves?


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I have a 98 OBW, and just bought my usual Purolator PureOne filter, and noticed that there is no anti-drainback valve. I looked at other brands, like Bosch, Mann that they sell in Bosch boxes, and something else too, and none have one. The only ones that do are the FRAMs and the WalMart brand. But I've been reading all kinds of crap about FRAMs, and WalMart brand doesn't seem to have a relief valve (the diagram shows some spring by the ADB valve and they claim that they do have both together--is this so?). So was wondering if the pros here have any suggestions. I don't want to buy the Subaru brand filters in bulk, don't plan on keeping the car long enough to need more than one extra, and don't really feel like shedding too much money to buy just one at the local stealership.

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The Subaru filters are probably the best ones to use. They're reasonably priced at the dealership I go to out here in Portland. I usually buy a couple at a time so its been a while since I've had to buy one, but I don't remember paying more than $5-$6 each, about on par with any bosch or wix filter. I'd shy away from anything but the basic fram filters, I've heard their tough guard ones are waaaay too restrictive and can cause oil pressure issues.

 

Forgot to answer your initial question: Yes, the Subaru filters do have an anti-drain back flap/valve.

Edited by scrap487
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I just bought some Mann filters from Amazon.com at $6.00 each and they do have anti-drainback valves as well as being full sized.

I have a couple of Denso filters which also have anti-drainback valves but are downsized. I doubt that the downsized filters are as efficient as the larger ones and aren't really good for more than 2-3k miles of use, even the Subaru branded ones.....not too cool if you're using a high quality synthetic oil with extended drain intervals. The larger filters should be good for up to 5k miles.

Edited by ergo
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I use napa filters. On my GL that has the filter sideways, the oil pressure gauge jumps right into life as the engine is cranking over. So it must have a drain back valve, otherwise half the oil would drain out of the filter.

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Thanks for the input all! I think I should add a few things to what I posted above. I don't have a particular brand loyalty on this, but I do like to have my things work right. So I looked through a few oil filter threads, and checked the specs and it seems that many filters have bypass valve settings far lower than what Subaru specifies. Many don't list theirs. Wix does have an ADB valve, but lists theirs bypass valve pressure at far less than Subaru. Purolator PureOne is the only one that's similar to the OEM specs, but no ADB :mad:. I couldn't find any info on STP/WalMart brand, Mann, or Bosch.

 

But if the Subaru brand is not that pricey, I think I'd just give the local dealer a call on Tue.. $6-7/filter is alright with me when it's the right thing, and not the "meet of exceed OEM specs" BS when it really doesn't.

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Funny, with the oil filter being on the bottom of the engine facing upwards, it holds oil like a glass on a table and I think wouldn't really need an ADB valve. Everytime I changed my oil I used whatever was on sale and it always had oil in it when I pulled it off.

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Funny, with the oil filter being on the bottom of the engine facing upwards, it holds oil like a glass on a table and I think wouldn't really need an ADB valve. Everytime I changed my oil I used whatever was on sale and it always had oil in it when I pulled it off.

 

The oil in the filter itself may not drain out, but oil in the oil-passages downstream of the filter could indeed drain back into the filter, leaving those oil-passages dry.

 

But all things considered, I wouldn't lose any sleep over it.

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Purolator used to make the white Subaru oil filters for Subaru of America so honestly, I wouldn't be concerned at all. They're the only "aftermarket" brand I know of that meets the bypass-valve spec for Subaru engines.

 

Can't go too bad with the blue Subaru Honeywell either, but it's up to you.

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The oil in the filter itself may not drain out, but oil in the oil-passages downstream of the filter could indeed drain back into the filter, leaving those oil-passages dry.

 

But all things considered, I wouldn't lose any sleep over it.

 

Oil passages run from bearings to bearings and dont really run dry. In a few cranks of the starter before the car runs it will fill the passages.

 

And a drainback valve isn't really needed on sooby engines, but nice to have.

 

For the record i use Mobil One filters.

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