Oil Pressure Gauge in My Car Reads Low – What Causes This?

Reader Question Hi Austin,

First off, I wanted to tell you what a fan of your website I’ve become. With as much work as I’ve had to put into my car, your website has been such a blessing and it’s really helped me avoid getting ripped off by mechanics who want to take advantage of a young college student with little knowledge about vehicles.

Here’s my dilemma. I drive a 1993 Pontiac Grand Am (V6, 3.3L) and I’ve noticed recently that I have very low oil pressure. When I first started noticing it, I continually checked my oil level, which has been consistantly fine, nowhere NEAR low. It finally has gotten to that point that when I accelerate, the highest it will go on the gauge is 60. When I’m braking, it’s practically at 0.

I didn’t have a problem with this until I recently had some work done by a mechanic I’ve come to find and trust immensely. I had my back brake lines replaced and my intake gasket replaced because my car was overheating and leaking coolant a lot. I had gotten an oil change prior to this and was getting near time for a new one when I had the work done – my oil pressure after the oil change I had done, I had noticed, was actually quite high.

When I got my car back from my mechanic, I noticed my oil pressure was lower than it was before, but not at a level to worry about. I checked my paperwork and noticed they had changed my oil. After driving it for a couple of weeks and noticing my pressure get lower and lower, I finally took it back to my mechanic yesterday and he took a look at it. I had told him about how they had changed my oil and asked if it could be in any relation to that or the work that they had done on my car.

He said that it was possible that when I had my own oil change done, they used a thicker, heavier oil and when my mechanic changed my oil, they used 10W-30. He suggested having them (my mechanic) change my oil and use something thicker to see if that helps.

I took it in this morning for that oil change. I had found out that the place that changed my oil previously had used 5W-30 and mentioned it to my mechanic so he agreed using that oil again. Well I have my car back now and unfortunately, this oil change has done very little to help the oil pressure and I’m worried.

What are some possible causes for low oil pressure and what kind of effects does it have on a car? The oil pressure is a LITTLE bit higher now, but not enough to make me feel comfortable. I know that my car needs a mass air flow sensor, could there be any correlation to that? Also, if you could throw out any ballpark figures with the different kind of fixes there might be, I’d really appreciate it as I’m a struggling college student with a car that continue to sucks money out of me.

Thanks and God bless,

Hellllloooooo Amber

How are you? Thanks for your email. I think I would go back to your new mechanic and ask them to replace the “oil pressure sending unit” and see if that helps your problem.

If the oil level is full, and you do not hear any abnormal engine noise, I would assume you either have a faulty oil pressure gauge in the dashboard (which is rare), or you have a faulty oil pressure sending unit, which tells the gauge inside the car how much pressure the oil pump is producing.

The sending unit is cheap and easy to replace as a guess, and would be the first thing I would do if you were at my shop. If that did not change things, I would manually check the oil pressure with a gauge AT THE ENGINE. This would tell me if there truly was a low pressure problem coming straight from the oil pump inside the motor.

At the bottom of your motor is the oil pump, and on the pump is a screen that acts as a filter. If the screen becomes clogged with dirt it will restrict the flow of oil to the pump, thus low oil pressure. If you truly do have a restriction or low oil pressure coming out of the oil pump you will usually hear noises in the engine because of lack of lubrication. Since you did not mention that, I would assume you have a sending unit issue. Let me know what happens.

Blessings back at ya,
Austin Davis

2 Comments on "Oil Pressure Gauge in My Car Reads Low – What Causes This?"

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  1. Branden says:

    I own a 96 jeep Grand Cherokee with an 318, I have never had any issues until just recently. I deceided to park the car over summer to save on car by driving my other car. Now winter has come to michigan and once again I wanted to pull my Jeep out for the four wheel drive. The promblem!!! The jeep starts right runs great oil pressure is fine for about 10 minutes and then goes to zero and the engine starts to make noise. Now if i shut it off and restart it The oil pressure is back but only intill I attempt to drive it or rev up the engine. My question? Could this just be a pluged oil pump screen???

    • Austin says:

      Yes this does sound like there could be a problem with the oil pump or screen clogged with oil sludge. If you hear engine tapping noise and have no oil pressure you most likely need to drop the oil pan and have the screen, oil pump and oil pump shaft replaced. You will also need an oil pan gasket set. I don’t recall how hard this job is and what is on the way of the oil pan removal. They do make a few products at your local parts store that might dissolve the sludge, although I have not had much luck with them you might want to try them before you spend big bucks at the mechanic. In the old days we would add a quart of varsol to the oil to help remove the sludge from the screen but it’s really not recommended these days as it will also remove sludge from valve guides and cause smoking problems later on.

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