Larger Oil filter didn't change oil pressure

[Saab9-3]

I installed a Amsoil Ea026 filter 1 year ago, which allowed me to add 2 liters to the sump. Some people suggested that it might affect oil pressure. I finally got around to installing my oil pressure gauge, and I am happy to report my oil pressure is well within normal spec.

Current fill is Lubromoly 0w40.

At cold start up, pressure is 70psi, at hot idle it sits at 22psi and on the hwy doing 120km/h at 2600rpm pressure sits nicely at 40psi.

Ill post pics of the gauge set up later.

 

[Pablo]

I would expect no change in oil pressure.

 

[dwendt44]

Oil pressure is controled by the relief valve; which is part of the oil pump assembly.
The filter would normally not have any thing to do with the system pressure.

 

[Gary Allan]

There should be no alteration to pressure with most types of oiling systems. Those who report this may have long term wear issues that make the filter a restriction of merit in some circumstances. Scored/leaking relief valves ..worn pump gears.

Can size can't alter oil pressure. The most it can do, by itself, is alter time to peak pressure if it empties.

The only other incidence of altered oil pressure due to filter selection, and this wasn't due to can size, was (IIRC) with a Titan V8. It has an oiling system that maintains a fixed oil pressure by manipulating the volume within limits. Wix or Purolator filters (one or the other) produced elevated pressures until warm. The only other time the pressure twitched was at higher rpm (like 3500+)

 

[Steve S]

What would cause a change in oil pressure?

 

[Gary Allan]

As I said, a defect. A leaking oil pump or a stuck or scored relief bore that allowed flow to be shunted. There, a difference in the density of a filter could alter pressure depending on where it's taken. That is, you're losing flow anyway ..and a filter, in that case, can actually alter flow.

In the case of the Titan V8, it has a "displacement on demand" (sorta) oil pump that keeps a level oil pressure within limits. Filters can alter the indicated pressure due to the volume changes..where they would not normally be perceived. I can't wrap around this setup since I haven't been able to assess cause and effect in person.

 

[Saab9-3]

http://video.google.ca/videoplay?do...940606&hl=en-CA

video of the gauge,

 

[Gary Allan]

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[Saab9-3]

http://video.google.ca/videoplay?docid=5371498904176940606

that should work

 

[TallPaul]

That's got to be a huge filter if it adds 2 liters to the capacity above and beyond the standard filter.

 

[dwendt44]

You change the filter at oil change time; changing the oil can affect oil presure. New oil it typically a bit thicker than used oil you dump out.
After a few thousand miles, the 'new' oil will be 'used' and the pressure will be the same as before.
My2¢

 

[Saab9-3]

Originally Posted By: TallPaul
That's got to be a huge filter if it adds 2 liters to the capacity above and beyond the standard filter.


Larger vs stock oil filter

 

[chevrofreak]

Holy [censored] man. That thing is big enough that I wouldn't change it for 50,000 miles!

 

[Saab9-3]

Lol

 

[TallPaul]

Originally Posted By: Saab9-3
Originally Posted By: TallPaul
That's got to be a huge filter if it adds 2 liters to the capacity above and beyond the standard filter.


Larger vs stock oil filter
I don't see size info on the Amsoil filter site, but it cross references with the Wix 51773, which is about 7 inches long by 3.7 wide. An old fashioned quart oil can is 5.5 inches high and about 3.9 inches wide. If you do the math, you'll see the 51773 holds a little over a quart. Unless the Amsoil version is twice as big as the Wix 51773 it does not hold 2 liters. Also you have to subtract the capacity of the stock filter, so you may have 2/3 quart increase in sump capacity.

 

[Saab9-3]

Tall Paul, It holds about 1.8 liters extra, but I overfilled just slightly above the max line (maybe 2mm). Maybe because there is more filter media, it absorbs more oil ? I understand your reasoning and the math makes sense, but I can take a pic of my dipstick and the empty 5 liter and 1 liter jug of oil

Edit: When I change my oil, the filter itself takes 1 liter of oil (could prob add more if I was patient). Then when I add the remaining 4 liters out of the 5 liter jug, my dipstick shows about 3/4 full. Then I just add the last liter to top everything up. Maybe there are secret trolls in the Ea filter that take on more oil

 

[TallPaul]

Well, kind of like what happened to me. About 3/4 quart less comes out with a drain than it takes to refill. There must be an oil troll involved in both cases. So long as it works, you're in good shape.