# Oil pressure at idle vs 2000 rpm spec



## 1200deluxe (Jul 11, 2018)

Hello - I have bought two stock CIS Cabriolets - one for parts, and one to restore. 

On the 1989 'restore' car, the idle is set to about 950 rpm, and after running for several minutes, the oil pressure light flashes, and pressure drops to about 1.5 bar. If I instead hold the car at 2000 rpm, the light goes out, and pressure is about 2.5 bar on the gauge. A mechanic friend tells me this is normal; me, I'm not so sure, so I thought I'd ask you.

For comparison, the 'parts' car is set to idle at 2000 rpm (which seems really high), and the light comes on when the key is first switched to 'on', before I switch to 'start', then goes out and stays out.

So here's the condensed question: is it normal for the oil pressure to go to 1.5 bar when a 1989 CIS-equipped Cabriolet is idling at around 1000 rpm, or should I immediately do a compression test, leak-down, test, or sell the car?

Thanks
Dave a.k.a. user 1200deluxe


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## Butcher (Jan 31, 2001)

I'm certain the OP is long gone, but for those that are searching this may help.

NEVER EVER trust the gauges in your car when you are diagnosing a problem. Test with known good tools/gauges. Although the oil pressure gauge in the car may read 1.5 bar, how do you know it is at 1.5 bar? The answer is you really do not know. 

Maybe the low oil pressure switch is working but the gauge is not right? Testing would tell you for certain. Once you confirm the gauge is reading correctly, then you can use that information as fact. 

This applies to the coolant temp gauge as well as the fuel gauge. 

My experience is that the oil pressure switch is working ok [and the gauge is not] and that there are worn bearings. A compression test would not really help you much there. There are larger oil pumps that can help cover that low oil pressure issue up.


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