winterheating wrote:putting 500ml extra oil in is more dangerous than running with oil level at minimum.
I'd agree, as it generates terrific crankase compression. I'd let it cool, dip oil again and if even slightly over the max, drop some out IMMEDIATELY. The engine will suffer no damage with the oil level anywhere between the max rite down to its minimum! (and shouldn't show the light either) just no less than the minimum.
I too would be suspecting a faulty pressure switch.
The only other possibility which is a long shot but has been known, is if something is has got into the sump and when joggled the right way starts to block the dip tube that the oil pump picks up oil from the bottom of the sump through. The only way to check is drop oil out, take sump and dip tube off and look. However, you'll need gasket sealer to replace the sump as its "stuck" not a replaceable gasket, and access to fresh oil or a way of catching / recycling yours.
Hope some of that makes sense,