2006 liberty 3.7 L oil weight recommendations

[TS7424]

when going to change oil in my jeep for the first time (just got it)
Why is it the owner's manual and Haynes repair manual recommend 5w-20 but the parts houses recommend 5W -30 ???

 

[tommudd]

Up until 2006 they suggested 5W30 and what I use in all of mine
after that they got stupid and in thinking we'll get an extra 1/10 of a gallon more mileage went to 5W20
Plus tolerances in the motor was supposedly tighter than earlier model