Oil pressure switch

[Fazerider]

The reason to wait a few minutes after warming up is so that most of that oil drains back into the sump.
Just for interest the increase in volume is :-
Volumetric expansion coefficient of engine oil is 0.00070 per deg C
Oil capacity say 2.7ltrs = 2,700c.c.
Lets say temperature difference from cold to warm is 40 deg C
Change in oil volume = 0.00070 x 2700 x 40 = 75.6c.c.
To use a previous measuring scale that’s about three normal egg cups worth.
I’ve no idea what that difference in volume represents in terms of height in the site glass and never bothered about it. Maybe I’ll have to check the oil level when cold and then again when warm after standing a few minutes and see if my calculation theory is total garbidge. 

The calculation sounds ok, but it’s only half the story as the aluminium alloy cases expand with heat too... so the sump gets bigger. :lol