I don't think there is an adverse 5W-40 for Kansas City weather. Pick one & go. Shell Rotella synthetic at Wally World does real well on your pocketbook despite it's smell from some exhaust systems. Want an uppity name brand.... try Amsoil, Red Line, Schaefers... etc.
We need a UOA on Belguim Castrol 5W-40. Sold at Auto Zone. Buy that one & get it analyzed from Blackstone at 6K on the odometer & paste the report here at BITOG.
It's sold at my local Autozone. I think it's $4.99/qt. I think it's a Group III synthetic, guessing from Havoline's MSDS for their full synthetic 10w30.
On the other hand, Rotella 5w40 is hard for me to find...the 15w40 is pretty common.
Chevron Supreme synthetic 5w40 & Seventy-six Lubricants 76 Pure synthetic 5w40 are both BAD 5w40 oils, & I challenge you to provide a single UOA of either proving otherwise.....wink wink
They're not bad oils.....Sorry; it was my attempt at dry humor(see the wink wink above). I posted my challenge in a thinly veiled attempt to get someone to hunt down a UOA from either of these two impossible-to-find oils.
No more humor attempts from me today. I will stick to my day job.