Oil filter relief valve question

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May 15, 2013
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My 1986 Nissan 300ZX has an external relief valve, so the oil filters for it are designed with NO internal relief valve. If I were to use a filter with all other factors the same - gasket size, thread size, etc. as the original, but with an internal 22 psi relief valve, what would be the downside, if any? basically I would then have redundant relief valves, however I do not know the external relief valve's PSI rating off hand, but I might be able to find it in the service manual.
 
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Oct 9, 2004
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Cincinnati, OH, USA
Similar to the GM small block engines, the filters come both ways, with & without a bypass-I really don't see a problem using one (in fact I have a PureOne with a bypass on my '93 GMC 6.2 now).
 
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It would help if you know the spec psi of the block bypass to know exactly what would happen. If the block bypass psi is less then, it would make little difference. If the block bypass is more then the filter 'could' bypass more often than the block spec. That said, bypass events are generally rare and of short duration. And 22 psi seems on the highish side compared to many other spec filter bypasses.
 
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The bypass spec of a filter relates to both the filtering material and the expected flow rates and expected delta-p's. Are you choosing a filter that is recommended by the filter manufacturer or just finding one that "fits"?
 
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Besides the possibility of the of the block bypass psi being greater (since unknown) than the filter bypass as I mentioned earlier, there is another consideration. If the filter you are running with the bypass is not the spec filter application, you will not be covered by the filter manufacturers filter warranty should some filter related happen to the engine. Read it here before many times, the first thing checked when a defective filter claim is made is to make sure it is the correct application. This vehicle specs a 3682/24457 both with no filter integral bypass. I'd say not being covered by a filter warranty is a downside. How big a downside is up to the user's view of the risk.
 
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I don't think there's much left on the warranty of his 1986 Nissan, but would surely agree that the correct filter for new vehicles is a good idea. I would probably use OEM ffilters during warranty period myself depending on the vehicle.
 
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Vehicle warranty is quite obviously not a concern. However as stated, not having a filter warranty using non spec application would preclude any claim/recourse the owner would have should a filter related failure be the source of an engine related issue. And also as said, how big a downside would be in the eye of the owner. But it is a risk consideration. And there have been several threads recently purporting some type of engine issue related to the filter on vehicles out of warranty . Filter application correctness first thing checked in any filter claim.
 

dnewton3

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I ran an FL400S (includes internal bypass) on my 1995 Villager which already has an in-engine bypass. The filter was not stock for the application, but it's what I wanted to use. Ran it for 15k miles miles. UOA and filter dissection showed no ill effects whatsoever. No issues; no worries. The opposite would present a big risk; running an engine will no filter bypass, and not having a filter internal bypass is a no-no. But the redundancy you ask of is no big deal.
 
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