Vortec 8.1L Oil Pressure/Filter question

[Burbman]

Last oil change I installed a Fram Ultra Guard since the Wal-Mart by me stopped carrying AC Delco filters. Local auto parts stores don't seem to carry the AC Delco filters either. Right after that I ordered some OEM PF-454 filters from Rock Auto so now I have a few on hand.

On a road trip to Chicago last week I noticed that the oil pressure was lower than normal....it was only running about 20 psi at idle and about 45 psi at 2500 RPM. I did an oil change yesterday with a little over 5k miles on the oil, and today I see the oil pressure is running about 10 psi higher, 30 psi at idle at about 55 psi at 2500 RPM with the AC Delco filter installed. This is where the oil pressure always was on this truck, so I consider this to be normal, so the oil pressure was running about 10 psi lower overall with the Fram filter.

The oil I am using is Mobil-1 5W30 Hi-Mileage formula.

I'm not sure if this is a function of having 5k miles on the filter or if the Fram filter is too restrictive vs. OEM. I never recall seeing a drop in oil pressure over the life of an oil filter. Does that mean the Fram is filtering better?

As an aside, I changed to synthetic at about 100k miles (160k on the truck now) and have noticed about 1 mpg improvement and I no longer get the infamous "piston slap" at startup...much quieter now. For the first 100k miles, I used regular dino oil with a 3k change interval, now I go 5k with synthetic.

Who makes the best oil filter these days anyway? The AC Delco's online were only $3.40 each, the Fram was $8+ at wally world, and I see they now have Bosch filters at $10+. Tempting to think that the more expensive filter is better, but as with anything else, that's more often marketing than actual quality.

I also did another Blackstone sample, and will post results when it comes back.

 

[daman]

Our farm 496 sees nothing but NAPA gold's, oil pressure is always on par with your readings.

 

[901Memphis]

The Fram Ultra is the best if you ask me. It's 99%+ efficient at 20 microns and 80% @5 microns with holding capacity for 15,000 mile intervals. If you're changing oil and filter at 5k miles though you would be under utilizing the Ultra.

I would recommend the Fram Tough Guard for the shorter interval and it's still rates at 99% efficient at 20 microns.

 

[BikeWhisperer]

I have not seen any drop in pressure going from an OEM filter to a Fram TG but different engines might act differently. The AC Delco filters like many OEM models are a little more "flow over filtration" and since you're using 5k OCI's I'd just use those since they seem to work for you.

I'd be curious to see if other high filtration synthetic filters (M1, RP, Amsoil) had the same effect on your Vortec

 

[dnewton3]

Wow ... We've come full circle here.

First, the OCOD had "cardboard" caps and would leak/bleed/fail at the cap.
Then the PureOne were being too restrictive.
Then Tearolators.
Now the Ultra is too restrictive.


...

Interesting for a first post.
Welcome to the site!

 

[Burbman]

So that was my question....is there, or could there be, any correlation between the filter and the oil pressure drop of 10 psi? Does that make the Fram TG a better or worse filter than the Delco, or is the psi drop along inconclusive?

I've never had any way to quantitatively compare filters besides price and what it says on the side of the box.... and Internet folklore like "Fram sucks" and "Amsoil is the best".

What I didn't pay attention to is what the oil pressure was when the TG was new...so I don't know if pressure was lower from the get go, or degraded over the 5k OCI. Huh....may have to run another one and take better notes.

I was told over on the RV forum that this was the place to learn about lubrication and filtration, so impart some knowledge on me!

 

[Chris B.]

Fram as a company is just to inconsistent to trust. Most of their products are junk. Just avoid Fram and use a quality Filter like WIX and you will be good to go.

 

[440Magnum]

I think there CAN be a correlation between filter and pressure drop, but that doesn't mean that the filter caused it in your case.

What were the ambient temperatures? What was the oil temperature? I know it was pretty cold in Chicago last week, if the filter was cold then the oil flowing through it could be a little thicker adding a little pressure drop across the media.

But 10 PSI is quite a bit. What kind of gauge is this? A good mechanical gauge with a copper capillary tube? Cheap mechanical gauge? Quality electrical gauge? Or (heaven forbid...) the factory dashboard electrical gauge? Electrical pressure sending units can also be skewed by temp. sometimes.

Bottom line, unless you can replicate it and repeat it under controlled circumstances and then change *just* the filter and see if the pressure changes, its pretty hard to draw a definite conclusion.

As for "who makes the best filter..." Oh geez!

If you want just my opinion:

Fram makes one of the best (the Ultra), and a bunch of the worse ones (ExtendedGuard- the plain orange can), and the rest are just OK.

Royal Purple sells (Champion makes it to their specs) a superb synthetic filter, as does Amsoil. But thou shalt pay out thine nose for these (actually they're only about $5-8 more than an Ultra, but its a big percentage change)

Wix are great for the money, but I don't care for their synthetic filter because its efficiency rating is much lower than the Fram Ultra, Royal Purple, Amsoil, and Purolator Synthetic.

Purolator- seems to have had a pretty big quality control issue with their "classic" (P-xxxxx numbers) and "PureOne" (PL-xxxxx) lines in recent years, but the synthetic (PSL-xxxxx) is excellent.

 

[CarbonSteel]

Originally Posted By: dnewton3
Wow ... We've come full circle here.

First, the OCOD had "cardboard" caps and would leak/bleed/fail at the cap.
Then the PureOne were being too restrictive.
Then Tearolators.
Now the Ultra is too restrictive.

...

x 1000

 

[ZeeOSix]

Originally Posted By: Burbman
On a road trip to Chicago last week I noticed that the oil pressure was lower than normal....it was only running about 20 psi at idle and about 45 psi at 2500 RPM. I did an oil change yesterday with a little over 5k miles on the oil, and today I see the oil pressure is running about 10 psi higher, 30 psi at idle at about 55 psi at 2500 RPM with the AC Delco filter installed. This is where the oil pressure always was on this truck, so I consider this to be normal, so the oil pressure was running about 10 psi lower overall with the Fram filter.


Questions:
1) What kind of vehicle is this?
2) Does it have a positive displacement oil pump?
3) What kind of oil pressure gauge is in the car (factory or aftermarket, digital or analog)?
4) Did you use the same Mobil-1 5W30 Hi-Mileage oil in both cases?
5) How do you know the oil was at the same exact temperature in both cases?
6) Where is the oil pressure sensor located (before or after the oil filter)?

Per my data collection, the oil pressure would only change ~6 PSI with a 75 deg F change in oil temperature (125 F to 200 F) - so it's not a strong factor.

With a positive displacement oil pump in good condition (ie, no internal leakage), and the pressure sensor located after the filter, the oil pressure should remain the same under the same exact conditions (oil viscosity/temp, engine RPM) regardless of the oil filter installed unless the filter made the oil pump hit pressure relief, which I highly doubt (ie, an Ultra on for only 5k miles).

If the pressure sensor is located before the filter, and/or the oil pump is some crazy new "pressure on demand" type, then the difference in oil pressure could be the filter.

And IF the pressure sensor is located BEFORE the filter, then a lower oil pressure means the filter is LESS restrictive.

Did you cut the filter open to look inside?

 

[crazyoildude]

This was my question also about the fram ultra i will find out sometime this week when i put one on instead of the motorcraft 820-s I have a real mechanical oil gauge that i will be watching hoping it will be a free flowing filter because it looks like a well built filter from just looking at it. Since new i used Motorcraft but since purolator makes motorcraft i won't be using them anymore because im afraid of the quality issues they have lately. This will be my first Fram in a long time. I Hope i don't find it too restrictive.

 

[crazyoildude]

the problem with napa golds in my area is that they have them behind the counter and i like to see my filters before buying them because i have gotten filters with dents in them and some other ones that i did not like for one reason or another, if i can't pick my own filter i don't buy them and there are a lot of people that feel the same way. Even at the shop when we rebuild an engine i look closely at the filter i take off the shelf.

 

[dnewton3]

Originally Posted By: crazyoildude
This will be my first Fram in a long time. I Hope i don't find it too restrictive.

First of all, please describe in detail just how you would know if the filter is "too restrictive"? What measuring tools and methodology would you be using? What level of restriction are you defining as "too" restrictive; please give us magnitudes you think are both acceptable and unacceptable.

Psssssssssstttttttttt .... Here's a little secret I'm going to share with you:
There is no filter made that is commonly available OTC that is going to be "too restrictive" in terms of performance for any typical application. Where and how this myth ever got started is beyond me, but it simply will not die.

DEATH BE UNTO THE RESTRICTIVE FILTER MYTH!

CAST OUT AND SLAY THE DEMONS OF FILTER IGNORANCE!

IN THE NAME OF BITOG I CONDEMN SUCH MYTHS TO THE DEPTHS OF THE INTERNET, TO BE NEVER HEARD AGAIN!

Originally Posted By: crazyoildude
the problem with napa golds in my area is that they have them behind the counter and i like to see my filters before buying them because i have gotten filters with dents in them and some other ones that i did not like for one reason or another, if i can't pick my own filter i don't buy them and there are a lot of people that feel the same way. Even at the shop when we rebuild an engine i look closely at the filter i take off the shelf.

The "problem with napa golds" is that you cannot see them?
Sir, if you cannot find the strength to ask to see and handle a product BEFORE agreeing to purchase and place into your shopping bag, then perhaps it's not the Napa store that has the problem ...

And let me get this straight so I comprehend your position of comments to understand fully your experience in the field ... You work at a shop that rebuilds engines, and you're the one that selects filters to install, but you don't understand the basic principles of hydraulic resistance and how a filter interacts with such a system?

Got it.

 

[Burbman]

Originally Posted By: ZeeOSix


Questions:
1) What kind of vehicle is this?
2) Does it have a positive displacement oil pump?
3) What kind of oil pressure gauge is in the car (factory or aftermarket, digital or analog)?
4) Did you use the same Mobil-1 5W30 Hi-Mileage oil in both cases?
5) How do you know the oil was at the same exact temperature in both cases?
6) Where is the oil pressure sensor located (before or after the oil filter)?


1) 2001 Suburban 2500 with 8.1L engine, 160k miles.

2&6) I would assume so...is there such a thing as a negative displacement oil pump?

This is how the engine lubrication process is explained in the service manual: Pump is mechanically driven and picks up oil in the pan through a pickup tube. Oil from the pump at the front of the engine is sent through the lower gallery to the rear of the engine, where it directed through the oil filter, then through the external oil cooler, then up to the upper galleries, where it lubricates the cam and crankshaft bearings, pushrods, and pressurizes the lifters. The pressure sensor is mounted at the upper rear of the block just below the intake manifold. Oil then returns to the pan via the crankshaft oil deflector.

3) Gauge is the factory analog gauge on the dash. Reads 0-80 psi and is labeled at 20, 40, 60 and 80, with hash marks in 5 psi intervals. It may not be accurate to the lb. but seems fairly precise based on historical consistency.

4) Have been using Mobil 1 since 100k miles and switched to hi-mileage formula around 130k.

5) The engine runs at constant temp when it warms up, according the analog dash gauge, and has a high capacity cooling system as part of the towing package on the Suburban. I would assume that oil temp would remain constant since it is being externally cooled as well, and maybe that is an incorrect assumption. I know I can monitor oil temp with my OBDII reader, I will check to see if there is much variance.

 

[Clevy]

Originally Posted By: Burbman
Originally Posted By: ZeeOSix


Questions:
1) What kind of vehicle is this?
2) Does it have a positive displacement oil pump?
3) What kind of oil pressure gauge is in the car (factory or aftermarket, digital or analog)?
4) Did you use the same Mobil-1 5W30 Hi-Mileage oil in both cases?
5) How do you know the oil was at the same exact temperature in both cases?
6) Where is the oil pressure sensor located (before or after the oil filter)?


1) 2001 Suburban 2500 with 8.1L engine, 160k miles.

2&6) I would assume so...is there such a thing as a negative displacement oil pump?

This is how the engine lubrication process is explained in the service manual: Pump is mechanically driven and picks up oil in the pan through a pickup tube. Oil from the pump at the front of the engine is sent through the lower gallery to the rear of the engine, where it directed through the oil filter, then through the external oil cooler, then up to the upper galleries, where it lubricates the cam and crankshaft bearings, pushrods, and pressurizes the lifters. The pressure sensor is mounted at the upper rear of the block just below the intake manifold. Oil then returns to the pan via the crankshaft oil deflector.

3) Gauge is the factory analog gauge on the dash. Reads 0-80 psi and is labeled at 20, 40, 60 and 80, with hash marks in 5 psi intervals. It may not be accurate to the lb. but seems fairly precise based on historical consistency.

4) Have been using Mobil 1 since 100k miles and switched to hi-mileage formula around 130k.

5) The engine runs at constant temp when it warms up, according the analog dash gauge, and has a high capacity cooling system as part of the towing package on the Suburban. I would assume that oil temp would remain constant since it is being externally cooled as well, and maybe that is an incorrect assumption. I know I can monitor oil temp with my OBDII reader, I will check to see if there is much variance.


You've got a brute for an engine. The oil maintains a steady state temp even under heavy loads,so just stick with whatever your already using if you haven't had any problems.
I like the euro spec 40 grades in the summertime when my trucks see much more pulling duty,but if your oil pressures are fine is stick with what's gotten you this far.
Chevy engines are built well,and every example in my fleet always drives great when I'm dropping off the Swiss cheese of a frame off at the wrecker.
SteveSRT has a fleet of chev vans. Holler at him for specifics. He's got the vans loaded with 10000 pounds rolling and the engine powers the electricity and the heating of the water(carpet cleaning) so his units are running at an extreme duty cycle yet he gets 1/2 million miles,plus 10-12 hours a day running,so if there's a tougher duty cycle I haven't seen it.

 

[440Magnum]

Originally Posted By: Burbman
Originally Posted By: ZeeOSix


Questions:
1) What kind of vehicle is this?
2) Does it have a positive displacement oil pump?
3) What kind of oil pressure gauge is in the car (factory or aftermarket, digital or analog)?
4) Did you use the same Mobil-1 5W30 Hi-Mileage oil in both cases?
5) How do you know the oil was at the same exact temperature in both cases?
6) Where is the oil pressure sensor located (before or after the oil filter)?


1) 2001 Suburban 2500 with 8.1L engine, 160k miles.

2&6) I would assume so...is there such a thing as a negative displacement oil pump?

This is how the engine lubrication process is explained in the service manual: Pump is mechanically driven and picks up oil in the pan through a pickup tube. Oil from the pump at the front of the engine is sent through the lower gallery to the rear of the engine, where it directed through the oil filter, then through the external oil cooler, then up to the upper galleries, where it lubricates the cam and crankshaft bearings, pushrods, and pressurizes the lifters. The pressure sensor is mounted at the upper rear of the block just below the intake manifold. Oil then returns to the pan via the crankshaft oil deflector.

3) Gauge is the factory analog gauge on the dash. Reads 0-80 psi and is labeled at 20, 40, 60 and 80, with hash marks in 5 psi intervals. It may not be accurate to the lb. but seems fairly precise based on historical consistency.

4) Have been using Mobil 1 since 100k miles and switched to hi-mileage formula around 130k.

5) The engine runs at constant temp when it warms up, according the analog dash gauge, and has a high capacity cooling system as part of the towing package on the Suburban. I would assume that oil temp would remain constant since it is being externally cooled as well, and maybe that is an incorrect assumption. I know I can monitor oil temp with my OBDII reader, I will check to see if there is much variance.


One thing left out- the pressure relief valve. That's probably located at the output of the oil pump (pre filter) and once it opens, the pump/valve combination is no longer "constant displacement," it becomes "constant pressure" and at that point pressure drop across the filter becomes, at least indirectly, measurable as a change in indicated oil pressure. But that only happens at high engine speed, the pressure relief valve should be closed at idle, so it theoretically shouldn't be able to see a filter-caused pressure difference at idle due to the pump forcing a fixed amount of oil through the system with every turn of the crank (which is what ZeeOSix was getting at, I'm pretty sure).

My problem is that there are still too many uncontrolled variables to blame the filter. The dash gauge is the weakest link- even good ones can vary. If there's a digital readout available through the computer, its probably better than the pointer on the dash, provided that the pressure sensor itself is consistent and accurate (which it may not be over a wide temperature range).

Oil temp probably varies a LOT more than you realize, since its not thermostatically regulated like coolant temp. My SRT has an oil-to-water oil cooler that will actually warm the oil when the oil temp is significantly below coolant temp, and an oil temperature option in the digital display area of the dash. But even with that setup I still see the oil temp vary by ~20 degrees summer vs. winter, and even more gentle cruising vs. hard driving. A whole lot of oil cooling occurs through the surface of the oil sump on any vehicle, and in really cold weather it can dominate the oil temperature.

 

[Burbman]

Got is, so zee-0-six meant to say "constant displacement" instead of "positive dislpacement", makes sense now. Good points, and there are actually two bypass valves, one at the pump to prevent over-pressurizing, and one at the filter to allow circulation to continue around a blocked filter. Oil cooling is similar on the Suburban, where oil is passed through the radiator on the left end and transmission fluid passes through the other right end. (Transmission fluid also has a secondary air cooler in series that sites in front of the radiator.)

Originally Posted By: 440Magnum
My problem is that there are still too many uncontrolled variables to blame the filter.


To be clear, I am absolutely NOT blaming the filter here...my question was whether it was possible for the filter to even be a suspect, or should I be looking elsewhere? Or maybe this is a non-event and I should just forget about it? Also wondering if anyone else has experienced similar pressure drop that was attributed to the filter?

We are certainly not going to draw many if any conclusions from my scenario given the number of unresolved variables that you mention. I do have another road trip planned for this weekend and temps should be similar to the last trip, so oil temps should be very close since the operating environment will be the same (no trailer, cruise set at 75 mph, similar outside temps).

Forgot to mention, nice stable of Mopar toys!

 

[crazyoildude]

if you read my posts you would see not only do i have an oil gauge that does not lie i also have ears that are trained in listening to engines for something like 35 years because that is all i do and my expertise is well regarded in engine land and also in the courts of not only New Jersey but other courts as well. If i say i feel it is restricted by the way an engine operates or sounds then i believe it to be so if you have any thoughts otherwise then so be it no shirt off my back. I also have a number of other things at my disposal but i don't need those things. I am installing the ultra on my vehicle and i will determine if i will use it again. I don't know what "myth" you are referring to and if you believe that restrictive filters don't exist and every filter is created the exact same flow wise then all the power to you. I post my beliefs as i see them i don't usually argue on an internet forum because sometimes it just gets old fast.

 

[ZeeOSix]

Originally Posted By: dnewton3
There is no filter made that is commonly available OTC that is going to be "too restrictive" in terms of performance for any typical application. Where and how this myth ever got started is beyond me, but it simply will not die.


I swear, everyone thinks the oiling system in their car works like the plumbing in their house. It doesn't, because a house's flow source is not from a positive displacement pump - it's from a pressure source, like a water tower (ie, gravity head system) or a pump that supplies endless volume at a certain max pressure.

For some reason, people think that if a filter is a little more restrictive, that the engine gets less oil flow ... but it doesn't except when the pump's in pressure relief, which rarely happens.

I've verified with 4 or 5 different filter brands on a car with digital oil temperature and pressure gauges that the "oil pressure vs engine RPM curve" never changes. I see zero difference in oil pressure using many different oil filter brands/models.

 

[ZeeOSix]

Originally Posted By: Burbman
Got is, so zee-0-six meant to say "constant displacement" instead of "positive dislpacement", makes sense now.


It's really a "positive displacement" oil pump, that puts out a fixed/constant volume of oil every time it rotates. The volume output of the oil pump changes with engine RPM, and that's why the oil pressure goes up with increased RPM - because the pump is forcing more volume through the engine which creates more oil pressure.

Google "positive displacement pump" and you'll see what they are all about.

Google Results for "positive displacement pump"