l have a Peugeot 405 and a gauge and the bottom-left of the dashboard has a scale that reads from ''mini'' to ''maxi''. What is this gauge, what does it measure?
The gauge is actually part of the instrument panel and is not a switch.

French cars are weird arent they. Anyways, mini in french means small and maxi means high, so l cannot help tell what it measures but that is what the scale is.

My advice is keep it in the middle, that has to be your safest bet! LOL!

AAhhhaaaa u fooled me by saying it was at the bottom left of the dashboard. l have a 1989 Peug 405 with Left hand steering. Your car is probably a right hand steer??

The GAUGE u mentioned is the OIL PRESSURE GAUGE. It only registers a mini or maxi pressure when u first start the car, then it falls to mini again. Do u see the line-drawing symbol for a dripping oil can?

There will rarely be a moment when u have too much oil pressure, unless u have accidently added TOO much, which is also bad.