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My oil pressure gauge is acting like a tachometer?

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Old 03-05-2010, 06:11 PM
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Default My oil pressure gauge is acting like a tachometer?

Can't say it'* ever done this before...

I was driving it today, and I don't think it was doing this initially...but then again I wasn't really paying attention either...but when I looked down I noticed that it was sweeping back and forth with engine rpms. It never dipped below 40, but it would push 90-100 psi before shifting, and I wasn't pushing it hard, maybe 2500 rpms or so. I think at idle it would dip down to 40-50 psi but I can't really remember. I had been driving it maybe 10-15 minutes when this happened. It never pegged 120 psi that I could see. It'* pretty warm outside, maybe 65 degrees, and I had driven it earlier in the day so the oil was fairly warm, however when I started the car it had cooled off enough that it was operating in open loop.

It continued to do that for a while, but it got more and more subdued as time went on. I was actually on my way to Advance Auto to get some motor oil for an upcoming oil change. Instead I returned here to go get my camera to take a video for you guys, but by then my OP had returned to normal. It still shifted with rpms, varying between 40-65 psi over a range of 600-2500 rpms. That'* pretty normal for it, I've always had pretty responsive oil pressure, but not 100 psi responsive, lol.

I should have used the video recorder in my phone, but oh well.

5k on Mobil 1 currently. Oil is pretty dark but my OLM hasn't set the change oil soon light yet.

What do you think might be happening here? Dying oil pressure sender? Sludge? My car is becoming sentient?
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Old 03-05-2010, 06:20 PM
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That is somewhat how mine shows now, at idle once it warms up it shows ~40psi then once you are on the gas it is in the 65psi range

mine started doing this after I did an oil change with motor flush about a 3 months ago, the sensor is about a year old so I'm thinking its just normal for the pressure to change, at least it makes sense to me that at idle the oil pump isn't moving as fast
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Old 03-05-2010, 06:49 PM
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When the oil is cold, it'* pretty thick, not as smooth flowing compared to when its warm. You will see a higher psi when its cold and less when its warmed up. OP will fluctuate with engine RPM. This is all normal.

Anything in the red zone is bad. Get it checked ASAP.
Anything showing really high could be normal, but the sensor is on its way out the door.
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Old 03-05-2010, 06:54 PM
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Nah, it'* never in the red zone. It doesn't drop below 40 psi.

I'm going to try a new sending unit with the oil change just to see, it'* a fairly inexpensive part and I have a feeling the one on there is a cheap part cause the guys that put it there cheaped me out on other items. I've never seen it change 30 psi on a gear shift before, lol.
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