Oil pressure drop after change

Joined
Jun 26, 2021
Messages
67
Location
North Minneapolis/St. Paul
When I had my 1998 Tahoe with the Vortec 350, my cold oil pressure varied around 10 psi depending on oil brand. Quaker State UD and RGT would be 40+ psi and PP would be just over 30psi. Ran the same Pure One filters and same 5w-30 viscosity the whole time. Had same results when switching back and forth between the brands. Never had any drivability or changes in engine noise, so never really worried about it. Sold the truck with 260k miles on it.
 
Joined
Jul 14, 2020
Messages
1,139
Because I can and winter is around the corner where I mostly do short trips and the thinner oil helps on those cold mornings and get up to operating temp. sooner. 5w20 in theory has less VII should help make it more shear resistant. I have read several reports from Blackstone and others that show there is no noticeable increase in wear using 5w20 vs 5w30 in this generation.

Also I don't live in a warm place like TX as you do, I live up in the mountains and it can get fairly cold here.
Why not a 0w then in that case? The 0w20s even typically seem to be made with arguably better base oils than 5w20.
Personally I use 0w40 as I have cold starts but also run the engine pretty hard on hills with lots of weight.
 
Joined
Apr 7, 2019
Messages
429
Location
VA
Why not a 0w then in that case? The 0w20s even typically seem to be made with arguably better base oils than 5w20.
Personally I use 0w40 as I have cold starts but also run the engine pretty hard on hills with lots of weight.
I don't currently have any 0 weights on hand but lots of 5w20 & 5w30 instead.
 
Joined
Nov 22, 2004
Messages
9,054
Location
Texas
Because I can and winter is around the corner where I mostly do short trips and the thinner oil helps on those cold mornings and get up to operating temp. sooner. 5w20 in theory has less VII should help make it more shear resistant. I have read several reports from Blackstone and others that show there is no noticeable increase in wear using 5w20 vs 5w30 in this generation.

Also I don't live in a warm place like TX as you do, I live up in the mountains and it can get fairly cold here.
Would you consider a 0w/30 as a possible better option all around?
 
Last edited:
Joined
Nov 22, 2004
Messages
9,054
Location
Texas
Because I can and winter is around the corner where I mostly do short trips and the thinner oil helps on those cold mornings and get up to operating temp. sooner. 5w20 in theory has less VII should help make it more shear resistant. I have read several reports from Blackstone and others that show there is no noticeable increase in wear using 5w20 vs 5w30 in this generation.

Also I don't live in a warm place like TX as you do, I live up in the mountains and it can get fairly cold here.
Yes you can, it's your choice. I used to live in your region and never needed thinner than 5w/30 which is recommended for your truck. Shear resistant or not - still a 20wt where a 30wt is fine and arguably better. But, opinions aside, I accept Blackstone's testing and good that you researched this. Living in Tx makes no difference really..heck we had 0 degree weather last winter lol
 

4WD

$50 site donor 2022
Joined
Sep 21, 2010
Messages
20,084
Location
Texas
I just changed my '04 w/ 5.3 using RGT 5w20, oil pressure is 40 psi hot but up to 50 psi at cold startup, also using Fram Ultra filter. I was leery of running this but read that lots of others are using 5w20 with no noticable difference in wear when having it tested.

Everything seems fine but right now I kinda wished I would've made one change instead of a different oil and filter at the same time, I mostly run Delco filters and have worked out well for me, I figured if it doesn't work out I can just dump it and go back to 5w30.
All the test data posted here indicated the Fram Ultra is not restrictive even with great filtration capabilities …
Thinking that’s why folks hated to see the media changed … Old or new version …?
 
Joined
Apr 7, 2019
Messages
429
Location
VA
All the test data posted here indicated the Fram Ultra is not restrictive even with great filtration capabilities …
Thinking that’s why folks hated to see the media changed … Old or new version …?
I mostly stick to Delco's, Purolator Pure One and Napa/Wix filters, I was at Walmart and yet they had lots of filters on the shelf but not much of a selection for my applications, for my car all they had the ST which is good filter but I like to stay with a name brand. I didn't use the Ultra to save money but the filter on these are bit of a pain, when you unscrew them the oil runs out and leaks all over the place, can't really grip the filter, you're covered in oil and runs down your arm. It's supposedly a 20k filter so even if I go 2 or 3 changes it's that much less I have to deal with it.

I haven't really checked out the Fram filters before but I literally just bought it so I'm sure it's the new style, I bought 2x of them and can post a picture of the one I didn't use. While the grip texture does help the oil pan is right there and you can't get your hand around it to even tighten it so I use those cup filter wrenches when changing it.

I really don't mind changing the oil on this truck, I use the rhino plastic ramps and it's really easy to do but that filter is the worst part. I even unbolted the skid plate because the way they designed it it really protects the drain bolt but when you drain it out all the oil it lays in there and you can't get your hand in there to simply wipe it out.
 
Joined
Apr 7, 2019
Messages
429
Location
VA
Would you consider a 0w/30 as a possible better option all around?
Not that I need a Dexos rated oil and that came out several years after my truck but I do like to run oils that have the certification and afaik the only 0w that I've seen is 0w20, I haven't checked the list to see if any 0w30 is listed but I know certain ones are excluded from even getting it ie: 10w30. I live in the northern part of the state but over by the WV side.

I just checked the list and Mobil 1 AFE 0w30 does have the certification but it's the only one.
 
Last edited:
Joined
Apr 7, 2019
Messages
429
Location
VA
What was the viscosity used and were they the same? Most likely it's nothing to worry about, the full synthetic should flow easier with less restriction hence the lower pressure. I don't know exactly which years were affected with the oil pickup o-ring but the earlier ones were. I was going to suggest the variable oil pump but it's already been asked if it had one or not.

Maybe the Wix is less restrictive than the Valvoline filter that you used previously.
 

4WD

$50 site donor 2022
Joined
Sep 21, 2010
Messages
20,084
Location
Texas
I mostly stick to Delco's, Purolator Pure One and Napa/Wix filters, I was at Walmart and yet they had lots of filters on the shelf but not much of a selection for my applications, for my car all they had the ST which is good filter but I like to stay with a name brand. I didn't use the Ultra to save money but the filter on these are bit of a pain, when you unscrew them the oil runs out and leaks all over the place, can't really grip the filter, you're covered in oil and runs down your arm. It's supposedly a 20k filter so even if I go 2 or 3 changes it's that much less I have to deal with it.

I haven't really checked out the Fram filters before but I literally just bought it so I'm sure it's the new style, I bought 2x of them and can post a picture of the one I didn't use. While the grip texture does help the oil pan is right there and you can't get your hand around it to even tighten it so I use those cup filter wrenches when changing it.

I really don't mind changing the oil on this truck, I use the rhino plastic ramps and it's really easy to do but that filter is the worst part. I even unbolted the skid plate because the way they designed it it really protects the drain bolt but when you drain it out all the oil it lays in there and you can't get your hand in there to simply wipe it out.
I have owned many generations of Chevy/GMC LT’s and SUV‘s … 2014 onward are certainly easier to change the oil and filter … wonder if free oil changes did not help due to dealership feedback …
 
Joined
Mar 4, 2017
Messages
23,934
Location
...
What was the viscosity used and were they the same? Most likely it's nothing to worry about, the full synthetic should flow easier with less restriction hence the lower pressure. I don't know exactly which years were affected with the oil pickup o-ring but the earlier ones were. I was going to suggest the variable oil pump but it's already been asked if it had one or not.

Maybe the Wix is less restrictive than the Valvoline filter that you used previously.


I would read the first comment.
 
Joined
Mar 12, 2015
Messages
22,265
Location
In the shop
I mostly stick to Delco's, Purolator Pure One and Napa/Wix filters, I was at Walmart and yet they had lots of filters on the shelf but not much of a selection for my applications, for my car all they had the ST which is good filter but I like to stay with a name brand. I didn't use the Ultra to save money but the filter on these are bit of a pain, when you unscrew them the oil runs out and leaks all over the place, can't really grip the filter, you're covered in oil and runs down your arm. It's supposedly a 20k filter so even if I go 2 or 3 changes it's that much less I have to deal with it.

I haven't really checked out the Fram filters before but I literally just bought it so I'm sure it's the new style, I bought 2x of them and can post a picture of the one I didn't use. While the grip texture does help the oil pan is right there and you can't get your hand around it to even tighten it so I use those cup filter wrenches when changing it.

I really don't mind changing the oil on this truck, I use the rhino plastic ramps and it's really easy to do but that filter is the worst part. I even unbolted the skid plate because the way they designed it it really protects the drain bolt but when you drain it out all the oil it lays in there and you can't get your hand in there to simply wipe it out.
I’ve ran Fram ultra multiple OCI’s as well as Fram Tough Guard for over 15k. Never a issue. Have 2 wire backed older ULTRA 4386 to use too
 

OVERKILL

$100 Site Donor 2021
Joined
Apr 28, 2008
Messages
52,987
Location
Ontario, Canada
Because I can and winter is around the corner where I mostly do short trips and the thinner oil helps on those cold mornings and get up to operating temp. sooner. 5w20 in theory has less VII should help make it more shear resistant. I have read several reports from Blackstone and others that show there is no noticeable increase in wear using 5w20 vs 5w30 in this generation.

Also I don't live in a warm place like TX as you do, I live up in the mountains and it can get fairly cold here.
Of course Blackstone doesn't condone deviating from whatever the OEM spec is and UOA's aren't designed to yield information that allows one to contrast wear between different lubricants.

That said, assuming you aren't seeing elevated oil temperatures, there's probably some margin there with you only doing short trips. Note that the thinner oil will not improve warm up, a heavier oil actually creates more heat because it creates more drag, which of course will also have a negative impact on fuel economy.

In a situation where an engine has been back-spec'd for a thinner lube (which implies significant testing by the OEM) I'd have no qualms about doing it either. Not sure if that applies in your case or not.
 
Joined
Apr 7, 2019
Messages
429
Location
VA
I’ve ran Fram ultra multiple OCI’s as well as Fram Tough Guard for over 15k. Never a issue. Have 2 wire backed older ULTRA 4386 to use too
Thanks I wasn't bashing on Fram or anything and seems like a well built filter for only $8.50 which is around 2x the cost of a Delco so even if I change it every other time it's all the same.
 

ZeeOSix

$100 site donor 2022
Joined
Jul 22, 2010
Messages
34,363
Location
PNW
And? That wouldn't come into play unless the filter is totally clogged.
Ture, but it wouldn't have to be "totally clogged" ... just enough to increase the delta-p across the media to be above the bypass valve setting. But the OP's oil pressure went down with the new oil and filter, so it's obviously not a clogged oil filter. If for some strange reason the filter was very clogged and restrictive, the the oil pressure could be less down stream of the filter is the added flow restriction caused the PD oil pump to hit relief pressure. The size of the bypass valve also can be a factor if it's too small to flow the bypassed oil without causing even more delta-p and putting the pump closer to pressure relief.

@Jamie86 ... did you cut open the old oil filter to look inside just to see if it looked normal?
 
Joined
Apr 7, 2019
Messages
429
Location
VA
Ture, but it wouldn't have to be "totally clogged" ... just enough to increase the delta-p across the media to be above the bypass valve setting. But the OP's oil pressure went down with the new oil and filter, so it's obviously not a clogged oil filter. If for some strange reason the filter was very clogged and restrictive, the the oil pressure could be less down stream of the filter is the added flow restriction caused the PD oil pump to hit relief pressure. The size of the bypass valve also can be a factor if it's too small to flow the bypassed oil without causing even more delta-p and putting the pump closer to pressure relief.

@Jamie86 ... did you cut open the old oil filter to look inside just to see if it looked normal?
It's quite possible the Maxlife blend cleaned out some gunk hence the higher pressure from before.

How long have you had the truck or do you know the maintenance history of it?
 
Top