Position of the By-Pass Valve in an Oil Filter

[Baracoa]

Below is information I received from Royal Purple concerning the location of the by-pass valve in an oil filter:

It makes no difference where the by-pass valve is located. Dirty unfiltered oil is being released through either way. The by-pass is a safety measure so as to allow the engine to never starve for oil. Unfiltered oil is way better than no oil or restricted oil.

No actual advantage exists from either by-pass location over the other. When the by-pass opens to allow for appropriate cold (thicker) oil flow volume, that unfiltered oil is not significantly cleaner with the by-pass in one location or another. It’s still unfiltered oil.

Some filters have an inferior filter media, typically cellulose (paper) or a blend. Others, such as the Royal Purple, use wire screen backed 100% synthetic micro glass filter media. These filters do not release significant amounts of the captured particles into the by-pass oil flow, so it really is of no consequence.

Oil filter manufacturers may also refer to micron particle size, but often do not share the capture rate for each particle size. Without the rate of capture associated with each particle size, this information is practically of no value.

Based on ISO 4548-12 multi-pass test methods, the Royal Purple filter efficiencies are as follows:

99% at 25 microns and larger
98.7% at 20 micros and larger
80% at 10 microns an larger

In addition to very fine filtration, the Royal Purple oil filters offer very high flow volume and are appropriate for most race applications. The Royal Purple oil filters are also built to withstand a burst pressure up to 600psi.

Please refer to the following link for Royal Purple Frequently Asked Questions:

http://www.royalpurpleconsumer.com/resources/faqs/oil-filter/

Based on the above information, I have come to the conclusion that there are many other more important features to look for, other than the position of the by-pass valve, when selecting an oil filter. Of much more importance is the filtering media and overall construction quality. From my own personal research on this matter, I have noticed that all the high-end filters, those intended for use with synthetic oil and 10,000 to 15,000 miles oil change intervals, have a dome-end by-pass valve and not a thread-end valve. Can that be conclusive evidence that it does not really matter where the by-pass valve is located? I would say probably yes.

 

[ZeeOSix]

I think Ford is probably the ones who started the whole base end bypass thing because most of their engines had filters mounted with base up.

I don't think it matters much where the bypass valve is located, unless the engine if very dirty and a lot of crud/sludge accumulates near the bypass valve (see figures below). In that case, I think it's entirely possible for a slug of crud/sludge to get swept through the bypass valve if it opens up a lot.

 

[Baracoa]

Ford and Chrysler seem to be the primary makers that recommend the use of filters that have a thread-end by-pass valve. I have not been able to find a high quality oil filter such as Royal Purple, Mobil 1, Wix XP, NAPA Platinum, and PurolatorBoss that offer such location of the valve. All these filters have a dome-end by-pass. Only the lower line of oil filters from Wix and NAPA have the thread-end valve location. Royal Purple has filters with the valve in both locations and they are all for long oil change intervals. If anyone knows of a high quality filter that can last 10,000 to 15,000 miles and that has the by-pass valve located in the thread-end, please let us know.

 

[CT8]

We fall for the marketing claims as gospel.

 

[ARCOgraphite]

RP is wrong, Base end bypass FTW! Their filters are too $$$. How to make a 4 dollar product a 10 $ product? Paint it purple!

 

[ARCOgraphite]

Main problem I see with base end bypass is that the unit displaces volume which would be better utilized by pleated media area in the small "hamster sized" form factors so prevalent today. One reason I run a Titan v8 filter on my Rogue. engine is still silly noisy during dead cold warmup.

 

[UncleDave]

I thought the titan filter was laughably small when I first looked at it being no different in size that the one in my maxima with the VQ35.

I believe there is some merit to this ad.

In a base up filter when debris to large to be trapped by the media is held against it under pressure when you remove that pressure it falls into suspension at the base of the dome, then on a cold morning start it's stirred up and when the bypass is opened even momentarily this slurry likely gets fed back into the engine due to its proximity

As is mentioned there are no premium filters I can find with a base plate bypass.

UD

 

[Nyogtha]

Fascinating the OP & UD ignore the Mobil 1 M1-301 filter (with base end bypass) in their analyses. How many more must there be?

 

[Baracoa]

Thank you for sharing information on the Mobil 1 M1-301. RP also has at least one filter that fits the Ford Focus and Fiesta that has the thread-end by-pass. But the RP for the Escape 6 Cylinder has it on the dome end. Purolator has all their filters with a dome end by-pass. It would be good to know why these differences. If thread-end by-pass is superior, why would companies also build filters with a dome-end by-pass. Is it related to the design of the specific filter for specific vehicles? Is it a cost issue? Preference of design?

 

[ZeeOSix]

Originally Posted By: Baracoa
If thread-end by-pass is superior, why would companies also build filters with a dome-end by-pass.


Because they expect people to change the oil and filter regularly to keep the engine very clean inside. When the engine is clean inside, then I don't think the location of the bypass valve will matter much.

 

[UncleDave]

Originally Posted By: Nyogtha
Fascinating the OP & UD ignore the Mobil 1 M1-301 filter (with base end bypass) in their analyses. How many more must there be?


Not so much "ignore" as didn't know or see that that particular filter was a base end bypass.
I look at a bunch of cut opens and vid of comparisons as well as do my own and just never saw it.
I like all my mobil1 product.

Ok There's one.

good question- how many more are there? Im going to see what I can find for my fleet.


UD

 

[UncleDave]

Bummer, that model doesn't fit on either my titan or the rx400.







UD

 

[Nyogtha]

Nor the vehicles in my household's fleet. An adaptor could be considered if there's room for the case (plus adaptor). Not worth it to me but maybe to someone.

My wife's 3.7L V6 Mustang has a horizontally mountex oil filter. IMO dome end bypass is preferable there anyway.

My 5.7L V8 Ram has a base up vertical filter and I have had experience where base end bypass was preferable during a Polar Vortex episode when I lived in the Great Lakes area. Under warranty I'm tied to a 6 month / 8K mile max O/FCI so I run a Mopar MO-899 standard OEM filter during the 6 colder months and something with higher effiviency the 6 warmer months. There's no room for something longer much less plus an adaptor plate.

A friend's 2.0L Audi A4 has a dome up filter on the top of the engine. All the filters I've seen for his application use dome end bypass (plus an anti-siphon valve) which makes sense to me for his application.

 

[Baracoa]

Additional information received from Royal Purple technical support concerning any alleged disadvantage to filters with a dome-end bypass valve indicated the following:

"Since we offer Royal Purple oil filters that utilize both by-pass design locations, I would have to say that neither design has an advantage of any significance, over the other by-pass location.

Unfortunately I do not have access to the actual engineering or manufacturing design parameters or the specific reasons the design team decided what they decided for choosing one by-pass design over the other on any specific filters.

In the motor enthusiast population there unfortunately seems to be a misguided notion that one location of the by-pass valve is better than another. The reality however is that there is no meaningful difference in the quality or cleanliness of oil that by-passes at the top or the bottom of the filter cartridge.

If you think about that actual fluid flow dynamics, there is always a boundary layer when the fluid is passing over an object and not through it. Nearly all of the fluid volume would remain in the flow of oil above this boundary layer of static stationary oil in and around the filter media pleats. Since this is where the particles are, no particle exchange of any meaningful significance can possibly take place."

I have now personally put this matter to rest. The position of the by-pass valve is no longer of importance to me. The overall quality of the filter is. This certainly allows for more filter choices.

 

[Baracoa]

Quality is usually associated with a higher cost whether it's related to oil filters or any other products. Royal Purple filters are more expensive than other brands that offer lower quality filters intended for shorter oil change intervals. K&N and Mobil 1 are of similar quality and price to Royal Purple. Investing an extra $5 to $10 dollars in a more reliable and higher quality filter is worth it compared to the potential risk and damage that a cheap oil filter can cause. Don't settle for less when protecting your car's engine.

 

[kschachn]

So Baracoa, do you work for Royal Purple or are you a dealer?

 

[Baracoa]

Royal Purple offers the RP 20-500 with a dome-end bypass but the RP 10-2835 has a thread-end bypass.

 

[Baracoa]

I do not work for Royal Purple. Actually I am not employed in the automotive industry. I am simply a car enthusiast who does some minor maintenance on my vehicles. I am sharing Royal Purple's comments since they provided good information about oil filters that I thought would be of good interest to the public. I contacted Purolator as well but they never returned my call or answered my emails.

 

[ARCOgraphite]

Unless you see the flow pattern run on a stack supercomputer, you don't know where boundary, stagnation and eddy exist. I worked with a liquid polymer injection mold designer in a small startup run by a bell labs scientist. Seen these models/anaylsis run real time. Not always easy to predict using common flow dynamics.

 

[Baracoa]

I just read the comments that a Purolator Engineer made regarding some concerns and questions that I had submitted to them about the location of the by-pass valve in an oil filter:

"Both by-pass valve designs function to not deprive the engine of the required volume/quantity of oil under the extreme startup conditions specifically in cold temperatures.

Regarding your concerns on the dome end-by pass valve design, I would like to clarify that the filter's media pores retain most of the dirt/contaminate. If the filter is not changed, and is already exceeding its life of change interval, the by-pass valve may stay open and circulate the dirt in the system. This is true for the other design with having thread end by-pass valve.

To note, Ford uses both relief valve designs in their product line. As for why one is used over the other, would be customer’s request, manufacturing process, and cost to name just a few reasons."