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-   -   Cold engine oil pressure (https://www.miataturbo.net/engine-performance-56/cold-engine-oil-pressure-49170/)

slowmx5 07-01-2010 03:37 PM

Cold engine oil pressure
 
I see as much as 80psi oil pressure on my engine when it is cold - using Motul's fully synthetic (double ester) 300v Power 5w40.

Gauge sensor is in stock location.

ISTR that the pressure relief valve should kick in at 60psi?? What pressures are others seeing? Pressure is normal once warmed up.

Joe Perez 07-01-2010 04:36 PM

Sounds like a sticky valve. One of my B6s shows close to 80-90 PSI when revved cold, the other reliably limits to 60. Haven't blown any oil filters yet, so I'm not seeing this as a huge problem.

The important question is: how's the pressure at idle?

edit: Wait a sec, don't you Brits read your oil pressure in bar? You're screwing with my prejudices here. :D

miatamania 07-01-2010 08:05 PM

We see really high cold pressures on our STis at work with that weight 300v...it is pretty thick when cold.

Fantastic oil but quite expensive.

fooger03 07-02-2010 01:01 PM

Isnt a new oil pressure relief valve specced to 90psi?

After installing a new pump, i got 90psi cold idle (and pressure relief valved above that) and about 15psi hot idle.

slowmx5 07-02-2010 01:57 PM


Originally Posted by Joe Perez (Post 596341)
Sounds like a sticky valve. One of my B6s shows close to 80-90 PSI when revved cold, the other reliably limits to 60. Haven't blown any oil filters yet, so I'm not seeing this as a huge problem.

The important question is: how's the pressure at idle?

edit: Wait a sec, don't you Brits read your oil pressure in bar? You're screwing with my prejudices here. :D

At least it sounds that I am not alone.

Cold start idle (1200rpm) I see 55 to 60psi, hot 27 to 29psi.

slowmx5 07-02-2010 01:59 PM


Originally Posted by fooger03 (Post 596596)
Isnt a new oil pressure relief valve specced to 90psi?

After installing a new pump, i got 90psi cold idle (and pressure relief valved above that) and about 15psi hot idle.

If true this is a very interesting piece of information. My pump was new when the engine was re-built. 15k or so miles ago?

slowmx5 07-02-2010 02:01 PM


Originally Posted by miatamania (Post 596440)
We see really high cold pressures on our STis at work with that weight 300v...it is pretty thick when cold.

Seems to be so. Shows notably higher oil pressure that the previous 0w30 Amsoil signature series oil - about 5psi or so.

Deatschwerks 07-07-2010 01:10 PM

A thicker oil is going to have a higher resistance to flow, so it will create a higher pressure in the system. A 5psi increase from 0W to 5W doesn't seem unusual.


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