Hi, I've been reading through the forum....lots of information. I'd like to get more life out of my Jeep and could use some help. I currently run Penzoil with a Fram filter (Wal-mart oil change) but I wanna start changing it myself. The dealer used Valvoline with a Mopar filter, better combo. I use 10w30 conventional oil. My 4.0 has 138K miles on the clock and I do alot of stop and go as well as cold start and have to go 50 mph right after start up. Any oil suggestions? Thanx!