Oil Pressure Fluctuation on Acceleration

[Nichiari2020]

Hi all,

I want to preface this by saying that I am very neurotic when it comes to my vehicles and tend to stare at gauges/temperatures constantly and worry about what they are reading. I posted around a year ago about oil pressure gauge flutter at steady throttle and the forums said normal and Ford didn't find anything; I've been able to put that out of my mind, but with my incessant watching of the oil pressure gauge, I've noticed other weird things. When the oil is at least 200F, I notice a fluctuation in the gauge under light to moderate acceleration. Say I start accelerating a bit in 5th at about 75mph or so, the gauge will go up to about 100psi and then drop a bit to say 95psi, then bounce back to 100ish, back and forth. As RPMs rise, this is lessened to a degree. But I have noticed it doing this around 4k rpm in 5th with moderate throttle. It appears to be completely steady at WOT. Oil level is full, and this oil only has 1300 miles on it, but the same flutter is there on brand new oil as well. Car has 52500 miles on her.

Am I just seeing the pressure spring relief in the pump opening and closing until enough load/flow is created to hold it open? Should I stop staring at the gauge and just drive? I'm leaning towards thinking that it's just the relief spring and have been thinking that way since I first noticed it; but here we are......

Thanks!

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[Bitten in '69]

Just a suggestion for your own wellbeing. Get some blue painter's tape. Apply it over the face of the gauge, and move on with life.

 

[Nichiari2020]

Just a suggestion for your own wellbeing. Get some blue painter's tape. Apply it over the face of the gauge, and move on with life.

Hahahahahahah yeah that would probably help me

 

[Skye]

My car is new to me and I'm still learning its characteristics. I maintain a log book where I make notes and comments that I can go back to and review, to track maintenance, keep a history and monitor for changes.

Your car appears to be working fine. Until something is out-of-spec, continue to use quality parts, follow the maintenance schedule and enjoy the car.

 

[bankyf]

This is exactly why very few cars actually come with functioning oil pressure gauges. Most are nothing more than a pressure switch that will move the needle to the center of the sweep once the preset pressure is achieved. Manufacturers learned a long time ago that functioning oil pressure gauges caused way more concern than necessary.

 

[Egparson202]

Hi all,

I want to preface this by saying that I am very neurotic when it comes to my vehicles and tend to stare at gauges/temperatures constantly and worry about what they are reading. I posted around a year ago about oil pressure gauge flutter at steady throttle and the forums said normal and Ford didn't find anything; I've been able to put that out of my mind, but with my incessant watching of the oil pressure gauge, I've noticed other weird things. When the oil is at least 200F, I notice a fluctuation in the gauge under light to moderate acceleration. Say I start accelerating a bit in 5th at about 75mph or so, the gauge will go up to about 100psi and then drop a bit to say 95psi, then bounce back to 100ish, back and forth. As RPMs rise, this is lessened to a degree. But I have noticed it doing this around 4k rpm in 5th with moderate throttle. It appears to be completely steady at WOT. Oil level is full, and this oil only has 1300 miles on it, but the same flutter is there on brand new oil as well. Car has 52500 miles on her.

Am I just seeing the pressure spring relief in the pump opening and closing until enough load/flow is created to hold it open? Should I stop staring at the gauge and just drive? I'm leaning towards thinking that it's just the relief spring and have been thinking that way since I first noticed it; but here we are......

Thanks!

You’re not alone in these concerns. However, this is nothing to worry about. As @bankyf shared, manufacturers realized long ago that the normal fluctuations of actual readings on things like temperature and pressures cause a degree of anxiety amongst a segment of owners. So, they replaced them with a combination of warning lights and gauges that have been stepped on to function as warning lights.

Your car sounds completely normal. Allow yourself to enjoy it with less worry.

 

[Rapid Red]

Take a pill, watch the road, seek psychic help, black out gauge pack, refer to idiot light warnings.

 

[Dr. JL]

Like others have stated, fluctuating oil pressure is not abnormal. The oil pressure in GR227 fluctuates like yours. The oil pressure in GR378 does not. Without a stated +/- oil pressure limit from Ford, I am only concerned if the oil pressure is low.

 

[Cobra Jet]

I've posted this before in other oil PSI threads.... so here's a repeat.
---

Oil PSI will change based on multiple conditions.

Oil PSI in ANY engine is always dependent upon operating temps, oil viscosity and SPEED/RPM. It's also dependent on extremely high tolerances built into these modern engines. Engines of days past (push rod engines) had "loose" tolerances and less internal parts where oil psi wasn't as high as seen in today's modern engines where build tolerances and specs are very "tight" and "close".

Also to note (for those not understanding oil psi or seeing such readings):
High oil psi upon initial startup is normal in every vehicle. The oil viscosity is thicker due to it sitting and dependent upon exterior seasonal temps (whether in a a garage or not). The colder the engine block, the thicker the oil will be, then as it warms up viscosity changes (thins out). As the oil does thin out and based on idle/speed/rpm/internal temps, yes the PSI will show lower readings. HOWEVER whether hot or cold, as long as those readings are within spec, there is NO concern.

Not every single Coyote (and Coyote Variant) is going to read the same oil psi @ X-interval (speed/rpm/idle) or at X-temps with X-viscosity, they just won't. Will they be within +/- 5-10psi of say the Ford spec, YES.

The oil psi specs below is for a bone stock S550 Coyote 5.0 right from Ford (I could not find a similar chart for a GT350 or GT350R):

That above charted PSI info is also based upon the standard recommended oil for the 5.0 Coyote.

—-
Here was an older thread regarding oil psi:
https://www.mustang6g.com/forums/threads/2018-mustang-gt-15-psi-oil-pressure-normal.109015/

For those new to S550 Coyotes and Coyote Variants with the stock analog factory PP oil psi gauge in center dash pod above the center console stack, the increments on it are garbage. IMO, Ford should have designed that oil psi gauge with better increments (more accuracy with better spread of the psi values, so it's not just a "on/off" and doesn't top out with the slightest blip of throttle response).

 

[Nichiari2020]

I appreciate all the replies, I guess I was worried because I was seeing the pressure gauge needle bounce back and forth a bit even though the engine rpms were rising. I will follow the advice given though and stop watching the gauge so much!

 

[Rapid Red]

I've posted this before in other oil PSI threads.... so here's a repeat.
---

Oil PSI will change based on multiple conditions.

Oil PSI in ANY engine is always dependent upon operating temps, oil viscosity and SPEED/RPM. It's also dependent on extremely high tolerances built into these modern engines. Engines of days past (push rod engines) had "loose" tolerances and less internal parts where oil psi wasn't as high as seen in today's modern engines where build tolerances and specs are very "tight" and "close".

Also to note (for those not understanding oil psi or seeing such readings):
High oil psi upon initial startup is normal in every vehicle. The oil viscosity is thicker due to it sitting and dependent upon exterior seasonal temps (whether in a a garage or not). The colder the engine block, the thicker the oil will be, then as it warms up viscosity changes (thins out). As the oil does thin out and based on idle/speed/rpm/internal temps, yes the PSI will show lower readings. HOWEVER whether hot or cold, as long as those readings are within spec, there is NO concern.

Not every single Coyote (and Coyote Variant) is going to read the same oil psi @ X-interval (speed/rpm/idle) or at X-temps with X-viscosity, they just won't. Will they be within +/- 5-10psi of say the Ford spec, YES.

The oil psi specs below is for a bone stock S550 Coyote 5.0 right from Ford (I could not find a similar chart for a GT350 or GT350R):

That above charted PSI info is also based upon the standard recommended oil for the 5.0 Coyote.

—-
Here was an older thread regarding oil psi:
https://www.mustang6g.com/forums/threads/2018-mustang-gt-15-psi-oil-pressure-normal.109015/

For those new to S550 Coyotes and Coyote Variants with the stock analog factory PP oil psi gauge in center dash pod above the center console stack, the increments on it are garbage. IMO, Ford should have designed that oil psi gauge with better increments (more accuracy with better spread of the psi values, so it's not just a "on/off" and doesn't top out with the slightest blip of throttle response).

Oil pressure varies ................ period end of story, no big mystery.

 

[Turbo23]

As one of my Chevy buddies always says, as long as the gauge needle is movin' you know there is still oil in there.

 

[Tomster]

The needle should not be bouncing at any given RPM. Oil pressure varies as stated above. If the needle is fluctuating at a given RPM, it could be the Guage, sensor, or pump. If you had pump failure most likely you would have zero pressure and the engine would size. A partial failure of the pump would most likely leat to a total failure bases upon the material the pump is made from (powdered metal). Powdered metal is very brittle, and any loose debris in the pump would lead to a catastrophic failure and FOD the engine along with oil starvation.

If the needle is fluctuating (like a nervous needle), I'd look into the Guage or oil pressure sensor. If it is simply varying with RPM, then that is normal and I wouldn't worry about it.

 

[Nichiari2020]

The needle should not be bouncing at any given RPM. Oil pressure varies as stated above. If the needle is fluctuating at a given RPM, it could be the Guage, sensor, or pump. If you had pump failure most likely you would have zero pressure and the engine would size. A partial failure of the pump would most likely leat to a total failure bases upon the material the pump is made from (powdered metal). Powdered metal is very brittle, and any loose debris in the pump would lead to a catastrophic failure and FOD the engine along with oil starvation.

If the needle is fluctuating (like a nervous needle), I'd look into the Guage or oil pressure sensor. If it is simply varying with RPM, then that is normal and I wouldn't worry about it.

Yeah the needle fluctuates back and forth as the RPMs rise when I'm not really hard on the throttle. Like the needle rises as expected when acceleration starts, but once it hits ~100+psi, I can see the needle drop slightly, then rise back up, etc. Getting harder into the throttle seems to steady it at around 100psi.

Could this be the relief valve in the pump? Pressure rises enough to open the spring a bit, it drops slightly as the relief opens, rises as it closes, etc etc.

 

[Dr. JL]

Like stated in my other post, the oil pressure reading on the center dash gauge in GR227 does tend to fluctuate. For reference, my original oil pump failed while idling in my driveway. FoMoCo replaced it under warranty. The new oil pump still produces fluctuating oil pressure (+/- 3 psi) on the center dash gauge. I note it, but don’t fret about it. The oil pressure on the instrument cluster does not fluctuate. This just might be the dash gauge issue.

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