Mistake to use filter w/ lower bypass than OEM?

[LoneRanger]

I have a new Subaru, which puts me in a slight predicament oil filter wise because Subaru dropped their OE oil filter supplier Tokyo Roki, which made a high quality filter, and gave the work to Honeywell Canada, which of course makes FRAM. The new Honeywell Subaru filters have been cut open by me and other enthusiasts and they are indeed classic FRAM pieces, replete with cardboard end caps.

So comes my predicament. The OE spec for bypass pressure is/was 23.2 psi, this has been quoted from the factory service manual. I can findno after market filter that offers this bypass rating except a Purolator L14460 or PL14460 however specified application for these filters stops at 2006 model year. Other Purolator filters are set for 14 - 18psi bypass.

I have a Wix 51365 on now that is 11psi bypass.

So I guess my question is does using a filter with a significantly lower bypass psi rating than the OE spec present any problems or risks?

I use 5W30 conventional oil and do not do extended drain intervals. I change oil and filter every 3750 on this vehicle.

I don't want to use the OEM filter now made by FRAM's maker, but if sticking to OE bypass psi spec is important then I guess I'll have to.

 

[HondaRD]

That's a good question LoneRanger. I wondered about the same thing when I decided to go with a wix oil filter rather than the blue Honeywell filter Subaru now uses on my wrx. I'm waiting for an updated service manual (or other literature) that may indicate what the bypass pressure spec is for the new OEM filter.

 

[sicko]

Hey I wanted to chime in with my experience regarding this matter, but first wanted to say that you should wait for more educated/expert opinion on this matter then my own.

Congrats on the new Subaru, I have an '09 Subaru Forester myself and have given some thought to this same question. Bypass PSI is actually part of the reason why I decided to get the PureOne filter b/c they had higher bypass psi then the Wix/NAPA Gold filters (well that and they were on sale so after rebate they were about $2.75).

First of all when checking around with what other Subaru owners are using, none of them who aren't using OEM filters have reported any problems. Many of them are using the PureOne or Wix/NAPA Gold and nobody has mentioned any issues that I've seen.

Also, my previous vehicle was an old Forester which I had for over 9 years. Other then a few times of taking it to the dealership, I took it for oil changes to a shop by my work which obviously did not use OEM filter. In all that time I never had an oil related issue with the vehicle. I abused the vehicle regularly and none of the issues I ever had with it were even remotely lubricant related. Overall the engine with pretty rock solid.

It's because of this that when I decided I was going to do my own oil changes on my new Forester that I picked up the PureOne filters since Subaru switched to the Honeywell/Fram filters. Part of me wishes I picked up a half dozen of the old black filters while they were available, but I've never heard of any filter related issue, or oil issues in general, with a Subaru (unless you count the headgasket issue of the late '90s early '00s). So I'm not worried about using the PureOnes or non-OEM filters.

But again, that's just my experience and thoughts on the matter, please wait for more expert opinions on the matter

 

[SuperBusa]

My thought is that if a filter manufacture lists an oil filter specifically for your car, then the by-pass pressure is set OK for that car.

The reason being is that IMO the filter by-pass setting is really based on the filter's design. Think about it ... the purpose of the by-pass is to open when the filtering element can't withstand a delta pressure above the by-pass valve's opening pressure. If the delta pressure across the filter increases due to contamination and/or high oil pump flow rate, then the by-pass starts to open. The filter manufacture knows what the safe level of pressure delta can be withstood for each filter design, and sets the by-pass appropriately.

A filter that has higher flow resistance should naturally have the by-pass pressure set higher so it doesn't open too soon. A filer that has a lower flow resistance can have the by-pass pressure set a little lower to obtain the same delta P across the filter element when the by-pass valve opens up.

 

[SuperBusa]

I wanted to add that on some cars the filter by-pass is built into the engine (Corvettes and other GM V8s for example use this method), and the oil filter has no by-pass valve.

Now think about this situation. The by-pass valve is a constant, so it might be more touchy on what filter you slap on an engine like this. If the filter is pretty restrictive it reduces the head room you have before the by-pass valve might start to operate, depending on where exactly the engine manufacture set the by-pass pressure at.

BTW, I've tried numerous times to find out what the GM LS6 engine's filter by-pass is set too. I can't find it anywhere. Anyone here know?

 

[Gary Allan]

Quote:
The reason being is that IMO the filter by-pass setting is really based on the filter's design. Think about it ... the purpose of the by-pass is to open when the filtering element can't withstand a delta pressure above the by-pass valve's opening pressure. If the delta pressure across the filter increases due to contamination and/or high oil pump flow rate, then the by-pass starts to open. The filter manufacture knows what the safe level of pressure delta can be withstood for each filter design, and sets the by-pass appropriately.


It's more complicated than that. While the media is constructed to withstand the bypass setting, the bypass setting may be specific for the engine in question. That is, the media is designed from that requirement on up.

I had often wondered why all of the Euro's had such extremely high bypass valve ratings and (typically) mesh reinforced media. I speculated that they must have some extreme volume/visc/whatever unique aspect to them that was mostly out of whack with our mundane (or even high performance) domestic iron.

Doug Hillary finally explained the reason. In their case, the engines may spec some very high visc oil ..at high volume and high pressure. That, in itself, would be no reason to have the higher bypass threshold. Some of these engines have bigger sumps and full warm up is well beyond the common 20 minute threshold. That would mean, if a lower bypass threshold was used (let's say 8-11) that the engine would be in perpetual bypass for most of its life.

Remember, the bypass on a filter is active when the oil pump is in relief. This is a perfect example of how this occurs. The ultra high visc at higher volumes may mean that you're peaking your 100 psi+ relief level (pump) and pushing 135+ until warm.

So, does this Subaru have an oil pressure gauge?

 

[edhackett]

Gary,

Based on the oil pressure gauge that I installed in my WRX, Subarus run at very "European" oil pressures. It was right at 100 psi cold, cold being about anything below fully warmed up. I did not see over 105 psi, which I am assuming was the oil pump relief pressure. It ran at ~60 psi hot and ~25 psi at hot idle. This was with a synthetic SAE 0W-30 or 10W-30. Subaru specs up to 20W-50.

I just wrestled with this same issue. I just ordered a dozen of the remaining Tokyo Roki filters to get my by until there is some actual use feedback and technical info on the new filters available.

Ed

 

[SuperBusa]

Originally Posted By: Gary Allan
Remember, the bypass on a filter is active when the oil pump is in relief. This is a perfect example of how this occurs. The ultra high visc at higher volumes may mean that you're peaking your 100 psi+ relief level (pump) and pushing 135+ until warm.


Yes, most likely that is true ... BUT, an oil filter could also go into by-pass without the oil pump going into by-pass. Remember that the filer by-pass is based on the delta P across the filter only. If a filter is very restrictive, and/or the oil pump is trying to pump thick oil through it (i.e., cold starts), or high volumes at high RPM, then the filter's by-pass is going to open if the delta P across the element exceeds the by-pass valve setting. This can happen independantly of the operation of the the oil pump's by-pass valve.

Here's and extreme example. Let's say a filter's by-pass is set to 12 psi. Let's say the oil pump's by-pass is set to 80 psi. Let's say the oil pump puts out 4 GPM of oil at a specific viscosity when the pumps produces 65 psi. Let's say the filter produces 16 psi delta across the element with this same oil flow. The filter went into by-pass without the pump going into by-pass.

This is why any filter that has the by-pass built in should be designed with a by-pass pressure that is specific for that filter design. The filter's by-pass setting must match the restriction and flow characteristics of the filter so it doesn't go into by-pass mode all the time.

 

[SuperBusa]

Originally Posted By: edhackett

Based on the oil pressure gauge that I installed in my WRX, Subarus run at very "European" oil pressures. It was right at 100 psi cold, cold being about anything below fully warmed up. I did not see over 105 psi, which I am assuming was the oil pump relief pressure. It ran at ~60 psi hot and ~25 psi at hot idle. This was with a synthetic SAE 0W-30 or 10W-30. Subaru specs up to 20W-50.


Like I tried to show above, what's going on inside the filter is all based on how the flow rate and viscosity of the oil going through it effects the delta P across the element. The filter's by-pass will only operate if the delta P is equal to or higher than the by-pass valve setting. The oil pressure could be 200 psi, and as long as the delta P acorss the filter was still below the by-pass setting then it wouldn't be in by-pass mode. The operation of the oil pump’s by-pass valve is completely independent from the oil filter’s by-pass valve.

Under those oil pressure conditions you mentioned above, you have no way of really knowing if the filter is going in to by-pass mode or not unless you can actually see your pressure "glitch" as the by-pass valve opens/closes.

 

[edhackett]

In fact there was a "glitch" at about 80 psi on a cold full cold start. I often wondered if that was the by-pass opening. There was no way to know for sure.

Without bench testing or on car testing using differential gauges, there is no way to know if a "generic" WIX filter with a 11-14 psi by-pass that is specified for Subaru, Ford, John Deere, Honda, Kubota, Nissan, etc. will be in bypass excessively at the pressure and flow characteristics of a Subaru. The 23.2 by-pass specification is not just for the Tokyo Roki filters. That has been the spec for the previous OEM filter makers that Subaru has used in the time that I have been driving them.

Will a bit longer time in by-pass(if that's the case) make any difference in the long run? Probably not. PureOne in an oversize will be my choice when the Tokyo Roki filters run out.

Ed

 

[SuperBusa]

Originally Posted By: edhackett
PureOne in an oversize will be my choice when the Tokyo Roki filters run out.


I know the PureOne by-pass setting is set higher than the WIX of the equivalent filter. Note - I was asking specifically about the PL14610 for my Nissan Altima. Here is a statement from Purolator when I asked their Tech Dept about it:

"L14610 family of filters which is meant for most of European applications that has OES filters with Relief valve setting specified as 1 bar (14.5 psi) with tolerance that RV opens upto 18 psi. Purolator's PL14610 and L14610 is in this specification range."

 

[SuperBusa]

Originally Posted By: LoneRanger

I have a Wix 51365 on now that is 11psi bypass.


I just noticed this ... your Subaru uses the same filter I'm looking at for the Altima.

The Wix 51356 is the longer version ... same as NAPA Gold 1356. The 51365 and 1365 is the short version ... it's about 1 inch shorter; looks like a bike filter.

That is the same filter my Nissan Altima takes. The PureOne PL14610 is the same as the Wix 51356 (long version).

The by-pass spec on the PureOne PL14610 shows as 14 - 18 psi.

http://www.purolatorautofilters.net/en-us/resources/Popup/Pages/PartDetailPopup.aspx?partnum=PL14610

 

[Gary Allan]

Quote:
Yes, most likely that is true ... BUT, an oil filter could also go into by-pass without the oil pump going into by-pass. Remember that the filer by-pass is based on the delta P across the filter only. If a filter is very restrictive, and/or the oil pump is trying to pump thick oil through it (i.e., cold starts), or high volumes at high RPM, then the filter's by-pass is going to open if the delta P across the element exceeds the by-pass valve setting. This can happen independantly of the operation of the the oil pump's by-pass valve.


Here's what you keep missing: Except for advanced age loading ..the ONLY TIME that you can have ANY appreciable PSID across the filter is when the OIL PUMP IS IN RELIEF!!!!!

When the oil pump isn't in relief ..you have a series circuit. If you understand (not saying you're inept if you don't) the basic series resistive circuit, the supply is dissipated over the total resistance. Any pressure drop (in electricity's or water's case) of any one element HAS to be in proportion to the other resistors/restrictions in the circuit.

They all have to add up to the supply. The ENGINE is MEGA MUCH MO BIGGAH PLAYAH in the scheme, yo!

That's why, out side of oil pump relief events, there's no such thing as a free flowing or restrictive filter while in use.

 

[SuperBusa]

Originally Posted By: Gary Allan

Here's what you keep missing: Except for advanced age loading ..the ONLY TIME that you can have ANY appreciable PSID across the filter is when the OIL PUMP IS IN RELIEF!!!!!


I can't buy into that statement without further research, as it really boils down to what the actual flowrate through the oil filter is and what pressure drop is associated with that said flowrate.

I'm sure there could instances when an oil filter goes into by-pass before the oil pump goes into by-pass. For instance, if an oil filter was designed with a very restrictive element and its by-pass was set very low, you could conceivably get into filter by-pass before the oil pump pressure relief kicked in, especially if it was set pretty high. It all depends on the combination of all these parameters in the system.

Originally Posted By: Gary Allan
When the oil pump isn't in relief ..you have a series circuit. If you understand (not saying you're inept if you don't) the basic series resistive circuit, the supply is dissipated over the total resistance. Any pressure drop (in electricity's or water's case) of any one element HAS to be in proportion to the other resistors/restrictions in the circuit.

They all have to add up to the supply. The ENGINE is MEGA MUCH MO BIGGAH PLAYAH in the scheme, yo!

That's why, out side of oil pump relief events, there's no such thing as a free flowing or restrictive filter while in use.


Again, it all depends on exactly how much flow rate is going through the series circuit. From what you are describing, you make it sound like the engine is a pin-hole compared to the oil filter. I find that hard to believe. I'd like to see what the actual flow rate of oil is going through an engine at high RPM ... I'm sure it's not trivial. If say it was 5 GPM, then that same 5 GPM MUST also go through the oil filter. If the oil filter can take 5 GPM without causing a delta P across it that's greater than its by-pass valve setting, then yes, it will not by-pass. But you make is sound like the engine part of the oil circuit is so restrictive that there is hardly any oil flow going anywhere ... that's hard to believe without seeing real numbers.

 

[Gary Allan]

Quote:
So I guess my question is does using a filter with a significantly lower bypass psi rating than the OE spec present any problems or risks?


Now this is opinion. If your relief (peak pressure) events are limited ..and/or of a small proportion of your total driving event, no. The higher bypass level should mere be attempting to keep 100% filtration over a broader span of start up/ warm up conditions.

I didn't spec out the dimensions, but is there anything stopping you from using the PL14460?

 

[Gary Allan]

Quote:
I'm sure there could instances when an oil filter goes into by-pass before the oil pump goes into by-pass. For instance, if an oil filter was designed with a very restrictive element and its by-pass was set very low, you could conceivably get into filter by-pass before the oil pump pressure relief kicked in, especially if it was set pretty high. It all depends on the combination of all these parameters in the system.


Yes. Here is when it may happen. The upper image would be an engine where the oil galleries are empty ..and therefore can provide no "back pressure". Again, in this instance, assuming the relief is not yet engaged ..there is no loss of flow.

Quote:
Again, it all depends on exactly how much flow rate is going through the series circuit. From what you are describing, you make it sound like the engine is a pin-hole compared to the oil filter. I find that hard to believe.


Well, think about it. When you see a gauge reading, where the sender is downstream of the filter (most are) ..do you think that the filter is adding a whole lot MORE?

Here's some images that may mean something to you.

More here..

Quote:
Again, it all depends on exactly how much flow rate is going through the series circuit.


Not at all. Let's take two graphs of pressure development. Remember, in a series resistive circuit ..all things are proportional and must add up to the supply. There may be some reactive (impedance) aspect to it ..at some point, but for the "mostly true" ..this is true. No matter what flow rate is pushed through the filter ..the pressure elevation that it generates in the fluid acceleration will be directly in proportion to the back pressure that the engine develops in the fluid having to accelerate through it.

So, if you look at the gauges above, As I apply more flow ..the filter will go up fractionally in ratio to the engine. It may be 2psid at peak ..and a few fractional inches of water column at idle.


While I'm not a disciplined expert (and there's a massive gaps in my education) trust me..this is something I know a WHOLE lot about. I've counted the teeth in a horse's mouth.

 

[SuperBusa]

Originally Posted By: Gary Allan
Quote:
Again, it all depends on exactly how much flow rate is going through the series circuit. From what you are describing, you make it sound like the engine is a pin-hole compared to the oil filter. I find that hard to believe.


Well, think about it. When you see a gauge reading, where the sender is downstream of the filter (most are) ..do you think that the filter is adding a whole lot MORE?


It's only adding a pressure drop that is solely dependant on the flow vs. PSID characteristics of that specific oil filter. The more restrictive the filter is to flow, the more pressure drop it causes, which directly detracts from the available pressure supplied to the engine down stream of the oil filter.

Originally Posted By: Gary Allan
Here's some images that may mean something to you.

If I'm reading the gauges right, I'd say the top set is the delta P across the filter at some RPM above idle ... call it delta P of 8~9 psi. The second photo is the delta P across the filter at some lower RPM ... call it a delta P of 4 psi.

All that proves is that the pressure drop across the filter increases as the flowrate through it increases with higher RPM. No big surprise there. That's what I've said in about every thread that we talk about oil filter flow performance ... the higher the flowrate through a filter, the higher the pressure drop across the filter.

Originally Posted By: Gary Allan
Quote:
Again, it all depends on exactly how much flow rate is going through the series circuit.


Not at all. Let's take two graphs of pressure development. Remember, in a series resistive circuit ..all things are proportional and must add up to the supply. There may be some reactive (impedance) aspect to it ..at some point, but for the "mostly true" ..this is true. No matter what flow rate is pushed through the filter ..the pressure elevation that it generates in the fluid acceleration will be directly in proportion to the back pressure that the engine develops in the fluid having to accelerate through it.


I like to think of it as "the filter delta P + the engine oil circuit delta P = the inlet pressure to the oil filter (which is basically the same as the oil pump's outlet pressure)." Just like in any flow scenario, if you have a fixed resistance (in this case oil filter + engine), as you increase the oil pressure (i.e., more engine RPM), the flowrate will increase and the associated pressure drop in each element of the circuit will be proportionally higher based on their specific flow vs. PSID characteristics.

 

[Gary Allan]

The images were to show you that I'm not talking out my [censored]

Not for you to read them for out of context dissection

The one with the spread was a relief event in progress. The top gauge had not peaked yet.

Idle hot on this thing was about (from memory)
24/26 20w-50
15/17 15w-40
12/11 xw-30
5/5.x xw-20
Close to zero/zero with 0w-10

 

[Jim Allen]

Gary: Didn't you present this info in detail in a post, or posts, some years ago? I gotta look this up. I had other things on my mind then.

If I'm getting this now, you're saying that the restriction is (almost) always in the engine, downstream of the filter, and rarely in the filter, and that as long as the restriction is downstream of the filter, the filter can't bypass? The only time the filter could bypass (and that would depend on it's actual setting) is during the time the lubrication system is filling and pressurizing. In that case oil viscosity would play a big part as well as the oil pump relief setting.

So, the bypass valve setting on the filter is as much an indicator of the filter's ability to withstand a pressure difference (i.e. continue to filter) as it is anything to do with the engine.

I should probably shut up before my foot goes in to the knee. I haven't had a caffeinated beverage yet and now I gotta go see if my vacationing neighbor's house has flooded or not. Major flood event occurring here now.

 

[Gary Allan]

Quote:
So, the bypass valve setting on the filter is as much an indicator of the filter's ability to withstand a pressure difference (i.e. continue to filter) as it is anything to do with the engine.


Absolutely ..but I'd word that the other way around. It's because the designers knew that they were going to be in extended pump relief ..with a high visc oil ..and they wanted to have the oil filtered, that they put a higher bypass valve setting and reinforced the media. Doug Hillary finally connected the dots for me on this.

What's the difference between these two filters?

Part Number: 51516
UPC Number: 765809515161
Principal Application: Ford/Lincoln/Mercury (81-09), Chrysler/Jeep/Mitsubishi (02-09), Mazda Trucks (94-07)
All Applications
Style: Spin-On Lube Filter
Service: Lube
Type: Full Flow
Media: Paper
Height: 4.828
Outer Diameter Top: 2.921
Outer Diameter Bottom: Closed
Thread Size: 3/4-16
By-Pass Valve Setting-PSI: 8-11
Anti-Drain Back Valve: Yes
Beta Ratio: 2/20=14/31
Burst Pressure-PSI: 275
Max Flow Rate: 7-9 GPM
Nominal Micron Rating: 20

Gasket Diameters
Number O.D. I.D. Thk.
Attached 2.734 2.430 0.226



Part Number: 51088
UPC Number: 765809510883
Principal Application: BMW (82-94), Mercedes-Benz (85-93)
All Applications
Style: Spin-On Lube Filter
Service: Lube
Type: Full Flow
Media: Paper
Height: 4.704
Outer Diameter Top: 2.983
Outer Diameter Bottom: Closed
Thread Size: 3/4-16
By-Pass Valve Setting-PSI: 30
Anti-Drain Back Valve: Yes
Burst Pressure-PSI: 280
Max Flow Rate: 7-9 GPM
Nominal Micron Rating: 19

Gasket Diameters
Number O.D. I.D. Thk.
Attached 2.740 2.370 0.275