: normal oil pressure fluctuation in driving? >>>



wamanning
10-04-06, 10:00 AM
i just noticed that my oil pressure reads just below the 1/2 marker @ idle and jumps to 3/4 marker when the throttle is applied. it stays @ 3/4 marker when driving, then drops back down just below 1/2 when i get off the gas. pressure up, down, up, down - all dependent on throttle being on/off.

is this normal?

i would expect the oil pressure to be constant, but what do i know?!

your sage input would be appreciated!

aldi
10-04-06, 10:09 AM
It's normal, 'cause the oil pressure depends on the revs of the oil pump (engine).
At idle there is low pressure. At higher rpm's the oil pressure increases till the pressure valve limits it.

wamanning
10-04-06, 08:24 PM
turns out that the oil pressure was apparently just equalizing. i'd just added a quart and noticed the fluctuation on the 1st start-up and drive.

on subsequent drives, the pressure was completely stable regardless of throttle position.

lakesidepark
10-08-06, 12:06 PM
well that raises the question again. I would expect it to be around 25-30psi at idle and up to 80psi at hard accelleration. 2500rpm around 40-60psi. The gauge range is 0-80 (middle is 40psi).

Now since I expect this from what my car does - tell me if its right. I sometimes wondered if I should ever see it go up to 80psi?

wamanning
10-08-06, 12:15 PM
now i'm watching mine more...and it does indeed fluctuate in normal driving based on throttle position :-)

no idea what the PSI values are, but it's @ ~1/4 hash-mark @ idle, and ~3/4 hash-mark when driving @ freeway speed.

crucatera00
10-08-06, 03:58 PM
Similiar thing happens in my catera except when i start up the car cold the needle reads around 60-70 and after about 15mins drive it will idle at about 20, is that normal
? Im probably going to have it ran for codes anyways

ewill3rd
10-09-06, 06:12 AM
Some hot idle oil pressures can be as low as 10 psi, be sure to check the factory specs.
Cold engine oil pressures can be as high as 80psi, it will fluctuate while driving.
There is a pressure regulator valve built into the pump but you guys are describing normal operation. Most people don't pay much heed to the oil pressure, it's a pretty rare failure on most cars these days.

lakesidepark
10-09-06, 12:47 PM
ewill is correct the hot oil pressure will be lower than the cool pressure. However it should not go below 21PSI with engine up to temp at idle. If it does this indicates wear to the bearing surfaces (worn engine) or a failing oil pump (or very thin oil).

I did notice that after I added my external oil cooler it stays much higher than before. Cooler oil is good (I run synthetic so its not so much a viscosity issue - but I am adding a thermostat to the cooler before winter so I can keep the car warmer!)

ewill3rd
10-09-06, 03:39 PM
Always check the specifications for the application.

inconnu
10-09-06, 04:26 PM
I guess if the oil pressure needle is not in the red zone you are alright.