Can I use a fuel pressure gauge to check my car's oil pressure? I don't have an oil pressure gauge but someone at Autozone said I could use my fuel pressure gauge. Is this true?

 

I need to use a gauge to check my oil pressure. The glowshift gauge, which I believe is probably wrong, is still showing high oil pressure.

It was originally showing 80 PSI and jumping to 100 if I rev'd it up. This was at all times, no matter how long the car had been running.

However, the water temp was wrong also so I checked on the thermostat and sure enough I found that the last owner didn't even have a thermostat in. I put in a 180 degree thermostat since summer isn't far off.

Now the glowshift gauges show the engine warms up to about 170, but never shows it reaching 180 for some reason.

The oil pressure now shows 80 PSI at max and drops to 60-69 psi at idle once the car has warmed up.

It shows the oil pressure does still go up to 80 psi if I rev it up.

I still suspect the gauges are all wrong so I want to make sure and start by manually checking the oil pressure.