Someone replied to a thread on this subject the other day with a suggestion about how to tell what the bottom end condition of an engine is like. The theory is that you run the engine (hopefully the oil pressure light will go out), then turn the ignition off. The instant that the engine stops turning, you turn the key back on again, and watch to see how long it takes for the oil pressure light to come back on.

The theory is, I suppose, that in a good engine, the light will take a while to come back on, whereas with a clapped out engine it'll be pretty much right away.

Any thoughts ? My 2.0l aircooled takes about 7 seconds to come back on (when the engine is good and warm), which seems like a fair while. My daughter's Daihatsu Charade takes about 2 seconds.
Nitram

Its probably not the best way to gauge the condition of the bottom end. Just get an oil pressure gauge. The amount of time for the light to come on depends on the viscosity of the oil which changes with temperature.