Re: 5w-20 requirement
5W20 was implemented by a few manufacturers to promote better fuel economy as it's a lighter oil. 10W40 will be fine to use. 5W30 is my favorite for all around summer/winter use. I run 5W20 in my Taurus with the 2V engine as I had a whole whack left over when I sold my gas station a few years ago.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!