Studies for how long different viscosity oils take to get up to operating temperature.

[ZeeOSix]

Are there any write-ups on the difference of time, or lack of difference, it takes for different viscosity oils to get up to operating temperature? My search wasn't very successful. Thanks.

Not enough to make any real difference. As others have said, thicker oil will warm-up slightly faster with all other factors held constant. If you want your oil to warm-up a little faster, then start driving it sooner than later after a cold start-up.

 

[CR94]

Viscosity is viscous friction. I would expect higher viscosity oil to heat up slightly faster. It takes more energy to pump thicker oil, that energy when expended is going to be heat.

That's partially correct, but the slight difference in energy expenditure will be more from shearing the oil in bearings, than from pumping it. In effect, you're burning slightly more fuel in exchange for heating thicker oil slightly faster that way.

 

[ZeeOSix]

People always seem to think it takes lots of "power" to pump the oil through an engine. If you look at the hydraulic HP equation and run some numbers, it's a lot lower than most will think. And the required power difference to pump one viscosity over the other is really pretty small when the oil is hot.