Originally Posted by WellOiled
If this is true, then many of those filters would be in bypass or at least very close to bypass at 34F and 3GPM.
Someone told me that on a cold winter morning ( 0*F) , an oil filter operates in by-pass mode for upwards of 15 minutes, until the oil gets some heat into it. Not sure if that's true, or how to prove that outside of a test stand. I'm sure the filter manufacturers have extreme cold flow data.
The first chart ( at a toasty 34*F ) would seem to support that statement.