Oil Pressure Gauge Going Kookoo

[PetulantSenior]

2019 GT
My oil pressure gauge is pegging mostly when cold. But when warm, if I hold an RMP, it will spike and return. When RPMs run up it will spike as well. Oil level is good. 2500 miles on fresh Mobile One. No check engine light.
Your thoughts?

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[Cobra Jet]

If the gauge is defective it could be the oil sending unit, or just a bad circuit board.

If you're really concerned, buy a true mechanical oil gauge and hook it up - see what the readouts are, because last thing you would want to overlook is something going south internally to the engine.


Other than mechanical issues .... I've posted the below before in other similar threads... here's a recap.

Oil PSI will change or "peg" based on multiple conditions.

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).

Oil PSI in ANY engine is always dependent upon operating temps, oil viscosity and RPM.

The oil psi specs below is for a bone stock S550 Coyote 5.0 right from Ford:

That 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/


IMO, Ford should have designed the oil psi gauge with better increments.

 

[Zrussian13]

Sounds normal to me. Higher pressure when cold. Low pressure when cruising. Nail it and pressure goes up to 90 plus.

 

[PetulantSenior]

Sounds normal to me. Higher pressure when cold. Low pressure when cruising. Nail it and pressure goes up to 90 plus.

Don't disagree ... however the spiking when holding a constant RPM concerns me.

 

[PetulantSenior]

If the gauge is defective it could be the oil sending unit, or just a bad circuit board.

If you're really concerned, buy a true mechanical oil gauge and hook it up - see what the readouts are, because last thing you would want to overlook is something going south internally to the engine.


Other than mechanical issues .... I've posted the below before in other similar threads... here's a recap.

Oil PSI will change or "peg" based on multiple conditions.

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).

Oil PSI in ANY engine is always dependent upon operating temps, oil viscosity and RPM.

The oil psi specs below is for a bone stock S550 Coyote 5.0 right from Ford:

That 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/


IMO, Ford should have designed the oil psi gauge with better increments.

Hey thank you!!! The link was most helpful.

 

[KingKona]

2019 GT
My oil pressure gauge is pegging mostly when cold. But when warm, if I hold an RMP, it will spike and return. When RPMs run up it will spike as well. Oil level is good. 2500 miles on fresh Mobile One. No check engine light.
Your thoughts?

How long have you had this car?

2018+ Coyotes have a electronic by-pass built into the oil pump. So the PSIs will drop when not needed.

 

[PetulantSenior]

How long have you had this car?

2018+ Coyotes have a electronic by-pass built into the oil pump. So the PSIs will drop when not needed.

 

[PetulantSenior]

March of '21

 

[Zrussian13]

Don't disagree ... however the spiking when holding a constant RPM concerns me.

What rpms are you holding when it spikes? Plus on fresher oil my gauge spikes more often then it does when it ages.

 

[DougS550]

Don't disagree ... however the spiking when holding a constant RPM concerns me.

Oil Pressure should never spike up-down when at steady RPM. I would replace the sending unit first and then go from their. I just changed one on my daughters 2017 Car.

 

[PetulantSenior]

What rpms are you holding when it spikes? Plus on fresher oil my gauge spikes more often then it does when it ages.

3500

 

[PetulantSenior]

Oil Pressure should never spike up-down when at steady RPM. I would replace the sending unit first and then go from their. I just changed one on my daughters 2017 Car.

Thanks ...

 

[Zrussian13]

3500

Just tried it on my way home from work. 85mph cruising in 6th at about 2400 rpms oil pressure is 30ish. If I drop 4th so my rpms go up just above 3500 my oil pressure jumps to 70 even though I'm holding a steady speed. I. On a fresh oil change from yesterday. Hows that compare to what yours is doing?

 

[shogun32]

3500

Is when the oil pressure bypass is closed. Behavior is precisely normal

Now if you quit with lugging your engine by keeping it above 3000 rpm like God intended you would have avoided all this consternation

 

[Cobra Jet]

Just tried it on my way home from work. 85mph cruising in 6th at about 2400 rpms oil pressure is 30ish. If I drop 4th so my rpms go up just above 3500 my oil pressure jumps to 70 even though I'm holding a steady speed. I. On a fresh oil change from yesterday. Hows that compare to what yours is doing?

You're dropping from 6th gear to 4th and at what speed? Anytime you do that (in any vehicle), the engine is going to be revving much higher making a 2-gear change to a lower gear like that... the RPM is going to be much higher in that moment, therefore increasing oil psi...

Not sure there's any issue at all, other than the need to understand engine dynamics and oiling system characteristics.

As I had posted above in Post #2 - Ford should have put better increments and needle calibration on the oil psi gauge, because ALL of those gauges can be maxed on initial start up and while driving if not at normal oil temps OR when playing around with the car at speed as noted.

If you want genuine accuracy, get rid of the factory oil psi "idiot" gauge and install a real mechanical psi gauge.

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