Consequences of a filter with a lower bypass psi?

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Patman

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I just recently found out that pretty much all of the oil filters that cross reference to the AC Delco PF64 oil filter (which my Corvette uses) also have a lower bypass pressure. The PF64 is set to 22psi, but from what I've found, the Ultra is around 15psi, and same with the Wix/NAPA Gold (unless you go to a longer version of it) There is even a technical service bulletin for the Corvette warning of using those filters with a lower bypass pressure. But their explanation makes it sound more like it would simply not be filtering the oil as often, so if anything I would think the lower psi would be better for harder driving because then the oil flow would be better. Does this make sense? For now I am going to be sticking to the PF64. But eventually I'd like to switch to the Fram Ultra.
 
My take on the TSB is GM wants to minimize the number of bypass events that would occur. The engines listed in the TSB all have variable displacement oil pumps and the pressure regulator feedback is taken down stream of the filter. The pressure surge on filters with low bypass settings would likely cause a bypass event. The 22 psi bypass setting filters specified by the TSB solve this issue. If I had one of those engines I would probably take GM’s advice.

GM stated the reason for the TSB was to avoid premature wear.
 
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Ummmmm... who accelerates WOT (wide open throttle) but then shifts at say, 2,500rpm and do this in 1st gear, 2nd, 3rd, etc?

When you think about pushing an engine HARD, usually mid - high RPMs come to mind, correct? At those RPM, the oil filter is in bypass mode, to sustain oil pressure. So can someone explain to me what the benefit would be of the oil filter going into bypass 5-7psi sooner? There's no benefit.

You want the oil filter to stay functional as long as possible in order for it to do it's job. I would hope that the auto manufacturers decided on the perfect bypass psi for both oil filtration and pressure.

I vote that you use the correct filter. Some of these companies make a one size fits all bypass spring (right in the middle of the range) and use it for both a 140hp Civic and 400hp Corvette. Seems silly to me.
 
Why not just stick with the AC Delco filter while your Vette is under warranty? They aren't bad filters.
 
The Subaru OEM filters that I am aware of as well as the blue cans from the US dealers have a higher bypass pressure setting and I have read through a lot of discussion about this topic regarding WRXs and FXTs.
One point that is brought up a lot is that the bypass pressure is a differential pressure across the filter itself, so it seems like the bypass should normally only be happening when the filter media itself is heavily loaded or the oil itself is very thick/cold. I suppose truly extreme driving could make all kinds of things one wouldn't expect happen, though.
I try to follow "the book" when I can and have a bunch of Tokyo Roki filters with the high bypass pressure setting (actually short/wide filters intended for the WRX, figure that is basically the same engine as mine), but am not sure if I will stick with such filters when my stock runs out as I haven't been able to find them cheap online like a did a couple of years ago. It would be nice to just get Frams at WM when I pick up oil, I don't like the blue cans from the dealer (which I think are made by Fram) because the case seems flimsy to me and I can feel it flexing when I screw it on.
 
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It's possible GM raised the bypass valve setting on the PF64 because the AC Delco filters area bit flow restrictive causing too much delta-p on cold starts. As Artem eluded to, there shouldn't be much oil flow and therefore delta-p during a start-up and low RPM use. Maybe GM figures guys are hammering their Vettes pretty hard with high RPM before the oil gets warmed up and therefore made the bypass valve setting higher to help reduce bypass events.
 
You've picked this subject for obvious reasons, an open bypass can and does let debris into the engine.

I recently changed a Lycoming IO360 that had the beginnings of the common cam lobe failure. A small sliver or two of metal was found in the filter on the last two 25 hour oil changes. Well within published acceptable limits.

However, one particular day, oil pressure was suddenly 5 PSI lower in cruise (and near nil on approach) . Exactly what you worry about happened. Upon cold start, the filter bypass and oil cooler bypass allowed a metal bit to enter the main oil gallery. Where it went directly to the #2 crankshaft main bearing. The metal bit ground around during flight, damaging the bearing and allowing excess oil flow past that bearing, lowering the oil pressure.

Three things might have prevented the disaster. 1) a higher bypass setting. 2) Thinner, synthetic oil, 3) Not revving up the engine upon cold start which was this pilots habit.

You can be sure the metal bits in the filter were not captured by the filter and simply remained in the filter canister, probably lying on the bottom, only to be swept up and into the engine by the oil flow.
 
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Originally Posted By: Virtus_Probi
The Subaru OEM filters that I am aware of as well as the blue cans from the US dealers have a higher bypass pressure setting and I have read through a lot of discussion about this topic regarding WRXs and FXTs.
One point that is brought up a lot is that the bypass pressure is a differential pressure across the filter itself, so it seems like the bypass should normally only be happening when the filter media itself is heavily loaded or the oil itself is very thick/cold. I suppose truly extreme driving could make all kinds of things one wouldn't expect happen, though.
I try to follow "the book" when I can and have a bunch of Tokyo Roki filters with the high bypass pressure setting (actually short/wide filters intended for the WRX, figure that is basically the same engine as mine), but am not sure if I will stick with such filters when my stock runs out as I haven't been able to find them cheap online like a did a couple of years ago. It would be nice to just get Frams at WM when I pick up oil, I don't like the blue cans from the dealer (which I think are made by Fram) because the case seems flimsy to me and I can feel it flexing when I screw it on.


Try a Wix filter in your Subaru, 57712XP XP for older EJ engines and WIX 57055 for the new FA. 22 + psi bypass and a very sold can.
 
Drive it nice when cold,
and it will probably never go into bypass, even at the lower setting.

https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3197094/



Originally Posted By: Cujet
Three things might have prevented the disaster. 1) a higher bypass setting. 2) Thinner, synthetic oil, 3) Not revving up the engine upon cold start which was this pilots habit.


Yes................. true for that Lycoming, but there shouldn't be ANY metal slivers floating around a modern car engine!

Don't fall for the "bypass event hysteria" -
chances are it's less than 5% of the total oil flow,
with the reaming 95% going through the media.
 
Originally Posted By: fozzdesy2001

Try a Wix filter in your Subaru, 57712XP XP for older EJ engines and WIX 57055 for the new FA. 22 + psi bypass and a very sold can.


I did buy a handful of the Wix/NAPA Golds recommended for the FA20DIT a while ago, ran one and found some oil in the "cup" my top mounted filter sits in well before it was time for my next change.
Felt like I had tightened it appropriately but cleaned up the mess and then went pretty much full gorilla on it to try to get the seeping to stop, had a fair amount of oil in the cup again with less than 100 more miles of driving. Replaced that one with a blue can from a Subaru dealer and sent the other Wix/NAPA Gold filters off to a guy who cut open virgin filters and posted details analyses of them on subaruforester.com, not sure if he ever posted results on those...told him it was fine with me if he just chose to use them as I had learned a lot from his posts on other filters, the filters I sent were a thank you for all that useful work he had posted for other Subaru owners.

I think I just had bad luck with the square cut gasket on that one particular filter not being quite right, but I have never oil seepage problems with the blue cans, a K&N filter, and Mazda and Subaru branded Tokyo Rokis.
 
Originally Posted By: Linctex
Drive it nice when cold,
and it will probably never go into bypass, even at the lower setting.

https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3197094/


Yes................. true for that Lycoming, but there shouldn't be ANY metal slivers floating around a modern car engine!

Don't fall for the "bypass event hysteria" -
chances are it's less than 5% of the total oil flow,
with the reaming 95% going through the media.


And yet Corvette engines have experienced a rash of bearing failures. Quote from the C7 forum: "engine problems that result in engines freezing up due to metal shards in the oil from poor milling process" .

It's well known that GM rarely produces a sterile engine, and that a pushrod, OHV V8 creates high levels of ferrous wear metals.

Particulates too small to see can and will damage bearings. Remember, bearings may be only have 5 ten thousandths clearance at times. A good filter simply reduces risk, and in my opinion, is absolutely necessary on GM products.
 
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Originally Posted By: Reddy45
Why not just stick with the AC Delco filter while your Vette is under warranty? They aren't bad filters.



The plan is still to run this filter during the warranty, but I do think the Ultra is a better built filter.
 
This is one of the dangers of running higher grade/thicker than recommended oil in cold conditions-bypass opens, bad things potentially can happen. Maybe go back to the in block bypass that older GM engines had & remove the filter bypass altogether?
 
Originally Posted By: bullwinkle
This is one of the dangers of running higher grade/thicker than recommended oil in cold conditions-bypass opens, bad things potentially can happen. Maybe go back to the in block bypass that older GM engines had & remove the filter bypass altogether?


I wonder why they abandoned that method of the having the bypass built into the block? My 2005 Corvette had the bypass in the block.
 
Originally Posted By: bullwinkle
This is one of the dangers of running higher grade/thicker than recommended oil in cold conditions-bypass opens, bad things potentially can happen. Maybe go back to the in block bypass that older GM engines had & remove the filter bypass altogether?


10w30 vs 0w40 when cold?
 
Originally Posted By: 04SE
I asked the same question and was told it was nothing to worry about?

5.3 L83 oil filter discussion


The GM statement was perfectly clear. They moved the oil sender from before filter to after filter. It's interesting Fram HP18 has the exact same 22 bypass as GM specifies. The HP18 would be a good choice for a large engine especially. The PF64 is also specified for a Spark.
 
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