Yesterday I started my truck with 10w40 after it had sat for 9 hours in 10F temp. I counted 3 seconds before the mechanical pressure gauge needle moved off zero. Maybe that is how long it took to build enough pressure to open the oil filter bypass valve. Anyway im curious how it goes for others with different oils. May be complicated because my pressure line fits beside oil filter, but on another vehicle it is at the opposite end of the engine and higher up and thus has a couple second delay even in warm weather. Anyway, if you have a real gauge list the temp, how long it sat, oil grade, oil brand/type, and seconds (counting one-one-thousand, two-one-thousand, ... OR by a clock), and any other possibly related info. This won't be scientific, but maybe we will learn something.