Bob Holton

My oil pressure normally holds at 60 lbs, this morning it holds at 40 ,, what happened, oil level is up ,10/40 oil not synthetic???????What should it be????

Siraniko

iTrader: (13)

thats common for a stock oil pressure regulator. when its cold, its above 60. after it warms up, it will drop by appox 10 psi.

cdrad51

40 psi at what rpm?

Bob Holton

40# at3000 rpm

cdrad51

hmm yeah that's a little low for 3000 rpm. Assuming you are using stock sender unit, make sure the contact is clean by removing it from the sender and wiping any oil and dirt off of it. Then reconnect and try again. Alternatively, do an oil pressure test as per the manual with a mech oil pressure gauge.

fast7

Is that from experience or from reading.

cdrad51

from experience.

LongDuck

These gauges are notoriously inaccurate when it comes to true reading. When Mazda decided to put an oil pressure gauge in, they figured it would be information as a Go-No-Go decision for the driver. The pressure readings are actually optimistic when it comes to actual pressure that the bearings and rotors would see.

That prominent mark at 60psi is where the oil pressure runs on cold-start, maybe just a bit higher. Once warmed up, the oil viscosity goes down and the oil is able to travel faster - this results in lower oil pressure; both real and on the Mazda gauge.

As long as you're showing pressure at all (i.e., the needle is off the peg at the lower limit), you're probably alright. If you notice that the oil pressure reading starts to fluctuate DRAMATICALLY when you drive (5-10 psi at idle, up to 75-80psi at 3k rpm), then the sending unit is going bad. Replacement of that copper 'mushroom' below the oil filter will likely get the reading back to a fairly constant '60'. HTH,