My 2006 Jeep Liberty Diesel came factory filled with synthetic as well. Synthetic does have certain characteristics that make it a good choice. Wether it is necessary or economical to do so, that depends on each situation. I like using a synthetic in my 2013 Silverado, but I use a synthetic blend in my Freightliner semi truck and compact tractor. Same brand for all of them since I can get commercial bulk pricing and free delivery to my front door, which makes them more cost effective than buying off the shelf at Wally World. Man, I sure love having so many choices. There is something for everyone and every situation.