Cold start problems (if they even exist) would be related to the winter rating. In your question above you are asking about two oils with the same rating.
I have 240,000 miles on two 3.6L Pentastars and they do not have cold start issues. I've started them in -22F with no problems.
Sure, if that makes you happy, but 5w-20 is just fine.
Instead of buying Lucas oil stabilizer, take the cash you would spend on it and light it on fire, it will be entertaining and you'll get a lot more value from just burning your money. Seriously, Lucas Oil Stabilizer has zero value or benefit to your engine.
Cold start problems are not related to cold weather. It is the meaning of the engines first start after sitting overnight.
Which is rarely ever a problem either. It’s often imagined to be one however.
That is a material, design or manufacturing defect which won't be cured by an oil. The only thing you might try to mitigate it is providing a high film thickness as in a higher HT/HS oil. The oil's winter rating would relate to pumpability, so as long as that wasn't improper for the expected starting temperatures, the oil will be pumped the same regardless of the grade.
I’ll stick my nose in and give my two cents - I ran 5W20 and fixed a bad rocker arm in my 2015 JK around 95K. As I recall, another poster had the same 3.6 and ran 5W30 its whole life. He had a bad rocker around 100K.
