Pressure drop when using pennzoil full synthetic

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One thing everyone is not cluing in on, is the OP stated "Would get slight lifter noise also using Pennzoil at idle. No lifter noise with Valvoline". If it is not the oils fault, why would this be stated? While I do not think the oil is at fault itself, If it were to blame, could it be because perhaps one is on the 'thick' side of 5w-30, and the other is on the 'thin' side?
 
This is repeatable. The oil was just changed from Valvoline with over 6000 miles less than 100 miles ago. Will be dumping that for Valvoline which will be the 3rd time. This truck runs straight through on highway from CT. to Cape Breton Island a distance if 900 miles each way straight thru stopping only for gas and food. This is done seven or eight times a year. For further info, over the past several years Kendall full synthetic has maintained the higher pressure as has the Valvoline. On the down side Mobil 1 falls into the low pressure with Pennzoil. If it's not something relating to the oil itself it doesn't make sense. I have done the Kendall and Mobil 1 myself so there was no switching going on here. The pressure ALWAYS returns to normal, the higher pressure, when it is replaced with Valvoline or Kendall. Didn't think I would have to get this far into this to explain. A slight drop I could understand with the possible difference in viscocity, but 20 lbs seems a bit much.
 
I saw no mention of the filters used. I doubt its the oil at all. I would question the oil pressure sending unit or the oil pickup seal.

Originally Posted by Tyler13
Thanks for letting me know this site is worthless.



Not a good way to start out here young man.
 
Originally Posted by Tyler13
Thanks for letting me know this site is worthless.


See ya!
 
Thank you all for your responses. I was hoping for an answer as to why this is happening. Was of the misconception that "bobistheoilguy" would have more than "fake news" as a reply. I won't waste anymore of your time.
 
Ive noticed significant changes in oil pressure between brands in my old diesel pickup. All running 15W40. So I don't think your crazy and I can't explain why it happens either.
 
Originally Posted by Tyler13
Thank you all for your responses. I was hoping for an answer as to why this is happening. Was of the misconception that "bobistheoilguy" would have more than "fake news" as a reply. I won't waste anymore of your time.



Its a forum, you have to weed through the responses. You got several. You have to consider the filters involved, and i saw no mention of ambient temps. Oil pressure will vary on a cold engine on start up and be different if its 15f or 60 f.

Also if the engine temp management is not consistent, i.e. the thermostat, that can cause variations as well. I mentioned the pressure sender as i have had to replace the one in my avalanche at only 75k miles. The other issue is the oil tube pick up seal.
 
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Originally Posted by spasm3
the oil pickup seal.

Ironically, this could make the pressure lower with thicker oil.
 
Originally Posted by MrMoody
Originally Posted by spasm3
the oil pickup seal.

Ironically, this could make the pressure lower with thicker oil.



probably so, just giving him all the variables on a vehicle we don't have in front of us.
 
Don't throw in towel just yet. This bunch can be a tuff crowd sometimes, but read and learn, there's some guys with lots of good knowledge hanging around here. I've been on the wrong end of few myself, but end the end they all are here to help.ðŸ‘
 
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Originally Posted by Tyler13
Thanks for letting me know this site is worthless.

Why is it that some new users who don't get the answers they expect take it personal and stomp their feet and throw a tantrum?

Why not just read the pretty accurate answers in this thread and make a careful consideration instead?

Unless of course that wasn't your objective in the first place, that I don't know.
 
Originally Posted by 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.


You missed the point. With a positive displacement oil pump (assume it's healthy) the same flow will be at the pressure sensor (especially at idle RPM) regardless of the filter's flow restriction. The only thing that happens with a more flow restrictive filter is the delta-p across the filter increases with the same flow. If the flow is the same coming out the filter at the point of the pressure sensor (ie, because of the positive displacement oil pump), then there will be no loss in measured oil pressure because of oil filter restriction.
 
Originally Posted by Tyler13
Thank you all for your responses. I was hoping for an answer as to why this is happening. Was of the misconception that "bobistheoilguy" would have more than "fake news" as a reply. I won't waste anymore of your time.


Have you done this same test after doing your own oil changes?

I'm assuming the oil pressure is being read at the same temperature each time (ie, full oil temperature after a long drive)?

Ultimate test would be to check it with a mechanical pressure gauge connected to the oil port on the block gallery. What kind of oil pressure gauge is in this vehicle?
 
My apologies if this was already mentioned and I missed it,what kind've vehicle is this? And does it have an actual real time gauge or is it a dummy gauge? Another scenario,but probably far fetched,maybe your oil pressure sending unit is going south and the two different add packs are wreaking havoc with the sending unit?
 
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