Pressure drop when using pennzoil full synthetic

[Tyler13]

Oil change at Firestone using Pennzoil full synthetic 5w30, idle oil pressure 18
2000 rpm 38
Oil change at Goodyear with Valvoline full synthetic 5w30, idle oil pressure 38
2000 rpm 58

This has happened twice. Valvoline maintained that oil pressure for the duration of use roughly 6000 miles all highway. Would get slight lifter noise also using Pennzoil at idle. No lifter noise with Valvoline. 2003 5.3 avalanche high mileage. What gives with the Pennzoil?

 

[SirTanon]

No way this is not the oil's fault. What kind/brand/model oil filter is Firestone using vs. Goodyear?

 

[Imp4]

Have you identified and eliminated all other variables??
It's a safe bet you still have some ground work to do here before reaching your conclusion...

Good luck!!!

 

[dave1251]

This post makes no sense.

 

[gathermewool]

Originally Posted by dave1251
This post makes no sense.


+1

Pressure change is NOT due to your selection of oil...I say this with 100% certainty.

 

[Danno]

Originally Posted by SirTanon
No way this is not the oil's fault. What kind/brand/model oil filter is Firestone using vs. Goodyear?

Probably should read...
"No way, this is not the oil's fault."

 

[46Harry]

Something is not right here. There is no way there can be that much variation in oil pressure between Pennzoil and Valvoline 5W-30 oils. I haven't used Valvoline oil in my 2010 Silverado 5.3 but I have used Pennzoil, Mobil 1 and Castrol full synthetic oil and I haven't seen any difference in oil pressure. If there was a difference in oil pressure I can't see it on the truck's oil pressure gauge. All I can think of is Goodyear is not using 5W-30 oil, but something with a higher viscosity. It's also possible that Firestone used the wrong oil too causing the pressure difference.

 

[gathermewool]

Originally Posted by Danno
Originally Posted by SirTanon
No way this is not the oil's fault. What kind/brand/model oil filter is Firestone using vs. Goodyear?

Probably should read...
"No way, this is not the oil's fault."


Huh? Are you saying the OP, "Probably should read..."?

 

[MParr]

It's not an oil problem. It's a 5.3 GM engine. Please folks, get a clue.

 

[Env1ous]

Originally Posted by gathermewool
Originally Posted by Danno
Originally Posted by SirTanon
No way this is not the oil's fault. What kind/brand/model oil filter is Firestone using vs. Goodyear?

Probably should read...
"No way, this is not the oil's fault."


Huh? Are you saying the OP, "Probably should read..."?


No. I believe it was an attempt to correct someone's grammar.

 

[SirTanon]

Originally Posted by Danno
Originally Posted by SirTanon
No way this is not the oil's fault. What kind/brand/model oil filter is Firestone using vs. Goodyear?

Probably should read...
"No way, this is not the oil's fault."


yeah.. I wrote it one way, went back to add "No way" in front, but forgot to take the 'not' out of the statement.

It should actually read:

"No way this is the oil's fault"

 

[csandste]

I'm pulling something out of my ear from a half century ago. Doubt if has any value, but here goes...

Had an old '69 Fiat 124 sport coupe. Can't remember oil brands, but one of 'em was Vedol (that ancient) which I bought by the case.

If I changed brands the idle pressure would go from almost nothing to approximately 30 lbs. I sort of figured out that the gauge was screwed up. Twenty nine pounds or less it would read zero to five. Thirty pounds and up it would read thirty and up.

Obviously the age of the incident is like someone talking about a Model T in the late sixties, but maybe instrumentation (although better than ancient times can misread as well.

 

[Oro_O]

Originally Posted by csandste
I sort of figured out that the gauge was screwed up. Twenty nine pounds or less it would read zero to five. Thirty pounds and up it would read thirty and up.


Was looking at a boat problem last week with similar instrumentation anomaly - but this time by design. Caterpillar had designed a temp gauge to "dampen" swing, but what it did was leap instantly from 180 to 195 with a small change in pressure.

So it's a possibility here.

 

[CarbonSteel]

Originally Posted by SirTanon
No way this is not the oil's fault. What kind/brand/model oil filter is Firestone using vs. Goodyear?
Agreed that it is not the oil and also wonder about the oil filter differences (if any).

 

[gathermewool]

Originally Posted by Env1ous
Originally Posted by gathermewool
Originally Posted by Danno
Originally Posted by SirTanon
No way this is not the oil's fault. What kind/brand/model oil filter is Firestone using vs. Goodyear?

Probably should read...
"No way, this is not the oil's fault."


Huh? Are you saying the OP, "Probably should read..."?


No. I believe it was an attempt to correct someone's grammar.



Haha, I read it the way I wanted to, including the appropriate comma!

 

[Powerglide]

Occam's razor says they used a lighter weight oil.

 

[ZeeOSix]

Originally Posted by 2015_PSD
Originally Posted by SirTanon
No way this is not the oil's fault. What kind/brand/model oil filter is Firestone using vs. Goodyear?
Agreed that it is not the oil and also wonder about the oil filter differences (if any).


A positive displacement oil pump is going to force the same oil flow volume through any filter at idle.

 

[ARCOgraphite]

Originally Posted by Powerglide
Occam's razor says they used a lighter weight oil.
I would agree here. But does not that engine use a 20 grade? Maybe he has stuff moving around the pan.

I would I've bought 30 grade oil that I swore was 20. In fact is was the last bottle of 5w30 Magnatec Synthetic. You dont see this on PQIA though from any major, though.

I wish I was still working in Wilmington were i had access to a Krebs viscometer and all kinds if other cool lab stuff. I would have to run the sample in an ice bath then extrapolate.

 

[Triple_Se7en]

Originally Posted by Tyler13
Oil change at Firestone using Pennzoil full synthetic 5w30, idle oil pressure 18
2000 rpm 38
Oil change at Goodyear with Valvoline full synthetic 5w30, idle oil pressure 38
2000 rpm 58

This has happened twice. Valvoline maintained that oil pressure for the duration of use roughly 6000 miles all highway. Would get slight lifter noise also using Pennzoil at idle. No lifter noise with Valvoline. 2003 5.3 avalanche high mileage. What gives with the Pennzoil?

Welcome to BITOG Tyler.
Did you physically watch them pour both of the brands you refer to, into the vehicle? Are you absolutely sure that either large bulk oil drum contains these products?
Are you aware that x-amount of oil change shops cheat the public sometimes and use cheap bulk oils instead? You may see Pennzoil on the front of that large oil drum. But that may not be what's inside.

The best step you can take when these things occur is to get both oils analyzed. Assumptions work best when proof is provided.

 

[MrMoody]

Originally Posted by ZeeOSix
A positive displacement oil pump is going to force the same oil flow volume through any filter at idle.

Even if this was true, much less on a worn pump, the pressure is measured after the filter, and different filters can have different delta-p at the same flow and viscosity. Not that it should be much on a new filter with hot oil.