coil spring vs. leaf spring

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Looking at fleet filters filter comaparison, I noticed they make a big deal out of the coil springs that Wix and Baldwin use. I never really gave it much thought. I use Motorcraft filters, 90% of the time and they have the leaf spring, never questioned it until now. So what are the pros and cons of the coil vs. leaf spring? Is the coil spring really necessary? Is the leaf spring perfectly adequate or is it just a way to make the filter cheaper without causing "to many" problems. http://www.fleetfilter.com/filter-comparisons.html
 
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The leaf is cheaper to make. It's a stamped piece of metal. I tend to think that the coil would be more accurate and reliable. That's an opinion. I personally (as in "in my case", due to my observations) don't fret over bypass ratings. In my testing a well used filter, in sub freezing temp, with high visc oil, merely approached the bypass threshold and the event was (what I would term) "transient" in that it was quickly reduced even under normal driving beyond start up/cold idle. The same filter produced near clean/new PSID levels as the oil warmed. All PSID events of merit only occurred when the oil pump was in relief. When you're gauge is peaked, you're at some elevated level of PSID. The level of PSID is related to how much oil flow is being shunted from the pump's output. Once the relief is closed, you should hardly be able to measure the differential. Sorry for the slight drift OT
 

MC5W20

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I am just trying to quantify why Wix and Baldwin would use the coil spring, as I would suspect the coil springs are more expensive. Is the performance benefit of them really there to justify the cost. Or is it just a marketing ploy. I am inclined to start buying wix filters exclusively. It is rare these days for a company to use an added cost item to make a superior product. Indeed, if that is what wix is doing then I am sold and will not search for other filter deals. Hey, if I remeber correctly the bypass valve only open on pressure differential, correct? If I got 40 PSI coming in and 30 PSI going out, and my bypass valve is 8 psi, then it would bypass. Is this correct?
 
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I'd say use the Wix if that's what you choose. Something to keep in mind though if the coil spring is your main reason for choosing the Wix, there are many high quality and even extended OCI filters that use a leaf spring. Royal Purple, M1/K&N and Bosch DP to name several. So while I'd agree that the coil spring is "better", it seems not a necessity for making a quality filter.
 

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Originally Posted By: MC5W20
Hey, if I remeber correctly the bypass valve only open on pressure differential, correct? If I got 40 PSI coming in and 30 PSI going out, and my bypass valve is 8 psi, then it would bypass. Is this correct?
Yes, that's correct. The bypass valve will only open when the pressure difference across the media is above the bypass valve opening setting.
 

MC5W20

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Originally Posted By: sayjac
if the coil spring is your main reason for choosing the Wix, there are many high quality and even extended OCI filters that use a leaf spring. Royal Purple, M1/K&N and Bosch DP to name several.
I'll try to clarify this. Its not the coil spring in itself I would make the decision for, but the fact of whether or not they are using a higher cost component to make a superior product. If using the coil spring actually aleviates a real problem ( even if it is only a problem in 1% of applications or 1% of useful life ) then I would use Wix filters because they are spending the money to make a good product - AND - not trying to find ways to make an acceptable product at lower cost. Not an easy distinction for a lot of people to make, but for my purposes I want to buy products from companies that are dedicated to making good products and not dedicated to making more money on products that simply just work or work good enough to sell. You mention KN, Mobil, royal purple and Bosch dp.. All filters I won't use. The most I have ever spent for an oil filter was $6 for a pure one. I have cut open a few Mobil 1, and I can't figure out why people pay $10 for an oil filter, there ain't nothing special about them, well maybe it has a thick can, but I don't see how that is a beneift. Which is kinda like my question, does the coil spring matter? Does it provide a real benefit? In its simplest form it boils down to this, if Wix is going to spend the money for coil spring, then they will also spend the money for other little extras that make the filter a quality product. So I am trying to quantify if the coil spring makes it a quality product or if it is a marketing ploy at a minimal cost to - lets say - tv commercials, print ads, racing sponsorships, rebates, promotional products, etc....
 
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I can't claim any particular expertise in bypass valve design and construction, but I have never read anything that said it is critical for a bypass to open at a certain pressure differential. It just needs to reliably open at some pressure differential before there will be either damage to the engine and/or damage to the filter. In other words, I suspect there is a range within which it can open which is fine. It may be one of those things where a coil spring is demonstrably better, but it is a refinement that serves little practical purpose.
 

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Originally Posted By: MC5W20
In its simplest form it boils down to this, if Wix is going to spend the money for coil spring, then they will also spend the money for other little extras that make the filter a quality product. So I am trying to quantify if the coil spring makes it a quality product or if it is a marketing ploy at a minimal cost to - lets say - tv commercials, print ads, racing sponsorships, rebates, promotional products, etc....
For the WIX or MAPA Gold filters that have the base end bypass valve design, I think they used a coil spring because that is the only spring that will inherently work in that design. What I'm saying is that the driver for a certain bypass spring design is based on other factors of the overall filter design. I think Purolator uses the flat "45 record adapter" spring design on their smaller filters because of the physical size (diameter) of the oil filter. On their larger diameter filters, they use the coil spring design ... so seems there is a design driver based on physical size. I have seen no data that says one design works better over another. As long as it opens and closes reliably when it's supposed to, then the design is good.
 
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Originally Posted By: MC5W20
Originally Posted By: sayjac
if the coil spring is your main reason for choosing the Wix, there are many high quality and even extended OCI filters that use a leaf spring. Royal Purple, M1/K&N and Bosch DP to name several.
I'll try to clarify this. Its not the coil spring in itself I would make the decision for, but the fact of whether or not they are using a higher cost component to make a superior product. If using the coil spring actually aleviates a real problem ( even if it is only a problem in 1% of applications or 1% of useful life ) then I would use Wix filters because they are spending the money to make a good product - AND - not trying to find ways to make an acceptable product at lower cost. Not an easy distinction for a lot of people to make, but for my purposes I want to buy products from companies that are dedicated to making good products and not dedicated to making more money on products that simply just work or work good enough to sell. You mention KN, Mobil, royal purple and Bosch dp.. All filters I won't use. The most I have ever spent for an oil filter was $6 for a pure one. I have cut open a few Mobil 1, and I can't figure out why people pay $10 for an oil filter, there ain't nothing special about them, well maybe it has a thick can, but I don't see how that is a beneift. Which is kinda like my question, does the coil spring matter? Does it provide a real benefit? In its simplest form it boils down to this, if Wix is going to spend the money for coil spring, then they will also spend the money for other little extras that make the filter a quality product. So I am trying to quantify if the coil spring makes it a quality product or if it is a marketing ploy at a minimal cost to - lets say - tv commercials, print ads, racing sponsorships, rebates, promotional products, etc....
Possibly WIX could spend a little extra on a 'quality' media....like PureOne and Bosch and Mobil 1....After all, 99.9% of the time the coil spring will never activate (if you change the filter at reasonable intervals)...but its the media that really counts in keeping your oil as clean as possible. ____________________________________ 2003 Ford Focus (2.3L Duratec) / 89K M1 5w20EP / OCI: 1 year or 12K+/- Filter: M1 EP
 
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Originally Posted By: MC5W20
You mention KN, Mobil, royal purple and Bosch dp.. All filters I won't use.
Won't use, or won't buy? I myself won't BUY them given that they're going price is typically $12+ which is too much if you ask me. But they're all known to be quality filters and I'd certainly USE any of them without hesitation.
 
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Originally Posted By: ZeeOSix
For the WIX or NAPA Gold filters that have the base end bypass valve design, I think they used a coil spring because that is the only spring that will inherently work in that design.
And, the Wix thread end bypass is held in place by that coil spring. Unlike the leaf spring Motorcraft/Mopar where the thread end bypass is integral to the filter core/centertube. That's why a coil spring design would be more important to the Wix design, IMO. For the OP, seems you've made up your mind. I only used the filter examples I did because they are designed extended OCI filters, 12-15k, using a leaf spring. Yes they cost more, but the point was that a quality filter, even extended OCI, can be made without a coil spring. Point missed. I could have used a Pure One which IMO, would have been apples to apples, but uses a leaf spring to hold the filter core. But as ZeeO says also uses a coil spring bypass design in the majority of their filters. Several smaller ones with the 45rpm adaptor. Like the Wix because it uses a coil spring, and implies quality, use it. To each there own, the coil spring is not enough to eliminate quality leaf spring filters for me.
 

MC5W20

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Originally Posted By: sayjac
Originally Posted By: ZeeOSix
For the WIX or NAPA Gold filters that have the base end bypass valve design, I think they used a coil spring because that is the only spring that will inherently work in that design.
And, the Wix thread end bypass is held in place by that coil spring. Unlike the leaf spring Motorcraft/Mopar where the thread end bypass is integral to the filter core/centertube. That's why a coil spring design would be more important to the Wix design, IMO. For the OP, seems you've made up your mind. I only used the filter examples I did because they are designed extended OCI filters, 12-15k, using a leaf spring. Yes they cost more, but the point was that a quality filter, even extended OCI, can be made without a coil spring. Point missed. I could have used a Pure One which IMO, would have been apples to apples, but uses a leaf spring to hold the filter core. But as ZeeO says also uses a coil spring bypass design in the majority of their filters. Several smaller ones with the 45rpm adaptor. Like the Wix because it uses a coil spring, and implies quality, use it. To each there own, the coil spring is not enough to eliminate quality leaf spring filters for me.
No point missed here. Your first sentence is what I wanted to know. I didn't realize there was a differnece between the Motorcraft leaf design and the wix coil spring design. I am glad I asked the question. To one of the other posters. I have cut open Wix filters before and the media looked good to me. That was a few years ago, has there media since changed? Mobil 1 filter is all I have experience with. I guess I won't buy them because of cost. I did get 4 of them for about $4 each on ebay. I ran them on a remote filter mount for transmission duty. They seemed ok, just couldn't see why an extra thick can was worth the extra dough.
 
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but I have never read anything that said it is critical for a bypass to open at a certain pressure differential. It just needs to reliably open at some pressure differential before there will be either damage to the engine and/or damage to the filter.
I'll give you a 50:50. Most engines it's not critical. Some it apparently is. Most engines get whatever generic offering the filter man provides. Others are quite specific in level and range. While Wix my generically use 8-11 (and according to their engineers, it's not a "range" as in process variable - it's onset to full open) some are a static "8" ...or 30 or whatever. Purolator does the same thing, the difference being that their common offering is (something like) 11-14psi. They too will adhere to exceptional OEM spec's where required. The only exception to this that I've ever seen is the high(er) bypass requirement for some turbo Subaru's. WIX is a top notch product. Don't hesitate to use one. About the only thing that WIX does have that Purolator has is nationwide, multi-vendor distribution on a retail level. That is, you won't find them on the shelves of PB, AA, AZ, WM, K-Mart. It's NAPA, CarQuest,..and Meijers ..and maybe some localized (and disappearing) small outfits.
 
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