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.

PureOne (Purolater), NAPG Gold and AC Delco are the only ones I usePressure drop is one method of gauging filtration effectiveness...but not in allcases..My 96 Sub's 7.4L has only had Mobil 1 5-30W it's whole life. Now at +163K of VERYhard driving and is now showing a little pressure dropUsed to peg it at startup. Now just over the 80PSI line coldUp to temp is is about 75PSI above 1200 RPM and 35-40PSI at idle.Key is to know what is normal and then when it isn't feeling well...can telllike you have noticedThe other part is that it went back up when you changed filtersI do NOT like FRAM engine oil fiters and won't use them

I use the PF1218 1 qt filter or a WIX alternate .

weathershak wrote:I use the PF1218 1 qt filter or a WIX alternate .The oversized filter won't fit in a 4WD application because of the front drive shaft and transfer case...

Amsoil filters are among the best at 20µ at 98.7%, Wix is also good at 20µ at 95%. Donaldson is 22µ at 98.7%. PureOne are hard to beat. 20µ at 99.9% (Amsoil used to have this same rating, but it changed in 2011.. not sure if there was a standard change??)AC Delco PF454 22µ at 99%. Those are all specific to this application. One should note that the PF1218 is larger, but MUCH less efficient. The PF1218 is rated at 35µ @ 99%, so I wouldn't run it over the PF454. The lower ratings may be AC Delco specific thou, as the Wix Cross (only one I looked at) is the same for both the 454 and 1218 cross.

We stopped using Fram filters years ago. We use Wix.

8.1 Oil Pressure and Filter | Good Sam Community

GeoBoy
Explorer
Mar 05, 2015
K&N oil filters are all about filtration and FLOW. Chevrolet engines are about flow and not necessarily high oil pressure.
Devocamper
Explorer
Mar 04, 2015
BurbMan wrote:
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.

I used to use K&N oil filters on my 8.1 chevy and they seemed to work well, not sure if they are the best but they say they are . If your interested I have 4 or 5 left over (new in the box) from when I changed trucks PM me if you would like to learn more.
ib516
Explorer II
Mar 04, 2015
I did an experiment on oil filters a while ago. FRAM was included.

Here's a link OIL FILTER AUTOPSY
AH64ID
Explorer
Mar 04, 2015
BurbMan wrote:
AH641, thanks for posting that, and making me feel lazy for not digging the service manual out of the garage and looking it up myself. But given that the 8.1 is not referenced tells me it may be different. I'll see if I can find it in my Helms manual and post.

It took a marine 8.1L mechanical service manual but I found it. There is a flow diagram with it, that looks very similar to what was already posted.

The oil is drawn from the oil pan through a pickup screen and tube, into the oil pump (7). Pressurized oil flows through the oil filter, into the oil cooler (5), back into the engine (6), up to the oil pressure gauge port (2) and rear crankshaft bearing, and is then distributed to the upper oil galleries.

I also found several sources that show min pressure as 5 at 1,000 and 10 at 2,000. I found a different min rating (2 ratings 1 manual) that says 6 at 1,000, 18 at 2,900 and 24 at 4,000.
BurbMan
Explorer II
Mar 04, 2015
AH641, thanks for posting that, and making me feel lazy for not digging the service manual out of the garage and looking it up myself. But given that the 8.1 is not referenced tells me it may be different. I'll see if I can find it in my Helms manual and post.
GeoBoy
Explorer
Mar 04, 2015
You couldn't pay me to run Fram filters. I run Amsoil, K&N or OEM oil filters only.
marquette
Explorer
Mar 03, 2015
hawkeye08 is correct. I meant flat tappet and roller cams. push rod was a bit of a generalization.
BenK
Explorer
Mar 03, 2015
Don...old habits die hard... :B

Will continue to HEET my tank before each test...if I remember and why
I know mine all pass way below the average 'car' in the state. Bugs
me that they label all of my vehicles as 'high emitter profile'...so
gotta get my readings down LOW

As for the loss of the traditional lube additives...have been using
Molybdenum Disulphide since the 60's when designing stuff for military
contracts

Found a consistent reference to MolyB and searched out their #1 source.
Called them and found in Calif and bought through our PO with a line
item for my personal use

It is now common in lots of oils from their factory. Continue to use
and almost gone my one and last time buy from them when they closed

Now testing Tungsten Disulphide and see similar results. Mainly with
small displacement. Runs cooler is the key indicator for me.

Part of my stock and even my grease gun is loaded with MolyB filled
MolyB Molybdenum

MolyB Molybdenum

This is from my first buy back in the 60's....found this can after the
divorce and moving
hawkeye-08
Explorer III
Mar 03, 2015
marquette wrote:
At one time I did a lot of reading about oil and filers on the Bob The Oil Guy forum. After reading about Fram filters (that I has been using) I switched to the NAPA Gold filter. It didn't raise my oil pressure as much as it did hold my oil pressure at it's high range. Meaning when I come to a stop or slow down the oil pressure doesn't drop the way it did with the Fram filter. From what I understood it has something to do with better back flow valves in better filters. The NAPA Gold is not unique to that it's just readily available for me. I also learned that it is important to match your oil to your engine. Push rod engines need different oil that roller cam engines. For example my old 4.0 Jeep push rod engine needs more zinc for wear than synthetic oil provides but a 4.7 Jeep will do better with synthetic because of the cam design. Much like this forum there is a lot to learn over on the oil forum if interested.

I think what you meant with push rod engines is actually flat tappet (lifters) vs the roller lifters. The new oils have the zinc and phosphates removed for better emissions and you either need to use additives or special oil that is meant for flat tappet engines (such as my 454 in my 73 Chev). You can have push rods with flat tappets or roller cams.
AH64ID
Explorer
Mar 03, 2015
Looking at where the filter is located, and where the sender is located it is most certainly post-filter. There is not one single reason to internally flow unfiltered oil up to the valley and back down to the filter, just to measure pressure pre-filter. Pre-filter and bypass pressure is really useless anyhow, it can potentially be very misleading to actual oil pressure, since a plugging filter will show high pressure and decrease pressure to the engine.

This is a SBC diagram, but how the 8.1L probably is plumbed as well. You can see the oil pressure sending unit in the top right of the diagram, post-filter.

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