Oil gauge panic
 

I just bought a 2004 rx8 as my first car. I thought the oil pressure gauge was a oil level meter (yes im an idiot) and it was at half way. Then drove quite a bit with it (300km). Naturally the oil p dropped over time and I panicked when I realised that it was oil pressure not level. I checked the level and it was above the low line. The oil light also did not show. So that could not really have hurt my engine, did it?

Now, i added 10w40, after i added the oil the level was between the full mark and the nearest hole. Then I started the car and the oil p shoot up way over the middle (between middle and H). Let it idle for a minute, shut it down and the next day the pressure dropped back between low and the middle. But higher than it was before filling.

I read on this site that the oil p gauge is a dummy gauge, but all participants to those threads show that the meter is off by just a few dots from the middle.

My question: How serious to take the oil-p gauge. I know when its at L or H its really bad. But where is the turning point to start panicking?

https://cimg0.ibsrv.net/gimg/www.rx8...41cd5c6688.jpg
right before i added up

You might have an electrical issue or the gauge is out of position for some reason. But the reading of the gauge means nothing. There is no sensor connected to it that is capable of measuring oil pressure, it's a simple on/off switch that is on if there is any pressure.

So you didn't hurt anything, nor does it matter that it shot up past middle (normal position for most cars) nor should you pay attention to it.
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The battery light being on might be a clue that you have an electrical issue and the gauge is reading low because the voltage to it is lower than normal.

Since this is your first car, you'll want to read up on rx8help.com about how to keep it running best.

The picture was taken when the car was not running, when I run the engine the battery light goes away immediately.

If the engine isn't running, there is no oil pressure, so your gauge should be full left. Sounds like the arrow is offset for some reason. Not worth trying to fix IMO.

But when the car is completely off the needle is all the way left at L. It moves to position before i start the engine. Same position when engine is running. So it wouldnt really be offset right?

That's.. strange, but still not worth fixing IMO. You could have a look at the wiring for the oil pressure switch on the engine to see if it's damaged. Logically, the gauge moves with the key in ON because current is going through it, but that's not supposed to happen if the oil switch is open (no pressure)... So that current is grounding somewhere.



Are there any modification on the car?

You may be running one of my mods which trully brings that gauge to life:
https://www.rotarytronics.com/produc...uge-deluxe-kit

To be sure... you should see a rather out of place wire coming out through the same hole as the bonnet release cable and either an oil filter adapter, or an extra sensor in the banjo bolt near the oil filter.

I dont think i have that mod installed. Previous owner did not know about it. I dont have the wire you described and also nothing on that bolt.

So i topped up the oil completely now, really dont want to add anymore. But the oil is still low. I am sure it used to be around the middle when i bought it.

Also for some reason, today the oil indeed only shows when the motor is running.
Look this is what the oil p is when idling.
https://cimg0.ibsrv.net/gimg/www.rx8...5b6a3e0852.jpg

Don't add more oil than the high mark on the dipstick. Oil pressure has nothing to do with the amount of oil in the engine and, at any rate, the car never came with an oil pressure sensor, this gauge is meaningless and should be ignored.
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Well... does your oil pressure gauge move with RPMs ? If not, then it isn't modded. If it does, then it is modded.
If it's not modded but sits as your pictures show it, then it is broken(the gauge itself, integral part of the cluster). At any rate, the stock gauge should not be given any attention.

I only have a modded exhaust. The oil-p meter does not move with different rpm's. Also does not move when oil is hot or cold. But it definitely moved this week from the middle towards the picture slowly over time with daily driving.

If you are that worried, you can install this kit for your car.

https://www.ebay.ca/itm/133829720471

+1

It's an 'indicator' and not a sensor. You'll have to install a pressure sensor on your own if you want the receive accurate / active oil pressure readings.