or just interpreting it wrong. They are understanding it, just maybe not explaining it in precise words.

 

That's not true. Temperature absolutely has bearing on it. But since we are splitting hairs...
Depending on brand oil, at a given temperature a 5w-XX may be thinner than a 0w-XX.

don't take my word for it. look up your favorite oil's PDS.
For a readily accessible example, Mobil 1
5w30 @40C, 61.7cSt
0w30 @40C, 62.9cSt
So on a hot summer day, the 5w30 is thinner at startup. Sub-freezing, it's a different story.

The designations of grade are not absolute values, they are ranges that oils have to fall into under certain conditions. And the relationships are not linear.

Use any top brand-name oil, keep it at the appropriate level on the dipstick and change it on a schedule as simple as following the oil life monitor and lubrication will not cause the early demise of the JK.

 

My wifes 2012 also states 5W-30. I use the 5W-20 in it. I think they found it works better all around on VVT engines. There is so much engineering on oil that these discussions will never have a positive, absolute answer!! I use the Mobil1 also.

 

I have a 2014 and use 5W20 but I also put two sticks of butter in with every oil change. I tried mazola but found that real butter worked better.

 

Chuck Norris pee works well too.

 

Yea but Chuck Norris does not have to pee.

 

that's not true. I just read that he peed in a semi truck gas tank and it is now known as Optimus Prime.

 

I know that this is getting old and we're beating a dead horse on the issue but I cannot accept your response, respectfully, of course. I'm not arguing, just disagreeing. Here's my take. We cannot possibly believe that the outside temperature, even if it's it gets 11- degrees outside, can affect the lower viscosity of oil. Sure, it will be slightly more viscous but when the average temperature of an engine reaches 300 plus degrees, this is a moot point. Remember, it's start-up that is where the major part of wear occurs. The thinner the oil, the better. So, a '0' rating on the low end is always a plus. I don't care how hot the outside temp is. Correct me if I'm wrong, but I believe that oil reaches it's best lubrication quality when it reaches 180 degrees. Of course, just my humble opinion. And I do respect yours.