Filter Bypass Valve

[S30Driver]

9 hours ago, Captain Obvious said:

What filter are you running? I'll see if I can dig up details on the internals.

 

This is the filter I have always used and currently installed ...

[Captain Obvious]

I should have expected that. Unfortunately I couldn't find any details about the internals of the Nissan stock filter. Not surprising, but unfortunate. So I don't know if Nissan included a bypass valve inside their filters or not.

The advantage of putting a bypass in the filter is you can use it in applications whether there is a bypass built into the block or not.

The disadvantage of putting a bypass in the filter is it takes up space which could otherwise be used by filter media. In other words, you can have more filter in the filter if you don't have to put a bypass valve inside.

So if your're positive that the application where you are putting the filter has a bypass valve elsewhere, you don't have to burn that space with at valve inside the filter. And since Nissan designed both sides of that equation, I don't know what they did.

But if you want to send me one, I would be happy to cut one open for you. 

And still... The claim that if you change your oil and filter at reasonable intervals and never let it on there so long that it clogs up the filter, it doesn't really matter.

[Captain Obvious]

I haven't personally vetted the details in the below, but here's a thread in which some people actually mounted pressure sensors before and after oil filters and measured the differential pressure across filters.

https://bobistheoilguy.com/forums/threads/oil-filter-pressure-differential-testing-psid.341925/

I didn't study it thoroughly, but a quick skim seems to support the theory that the delta-P over the filter media on any clean filter is very low and not enough to open the bypass valve. And that delta-P is pretty much unaffected by oil temp and only goes up as the filter becomes dirty.