I use synthetic 0W-30 in my '06 3.7L and it does greet. It may be higher priced but it does the job. I have it in my motorcycle as well and that made a world of difference in the idle and start up.
2.5 RR Lift, 265/70r17 BFG AT, Edelbrock Extreme IAS Shocks, 1.5 Wheel Spacers, K&N Drop-in,
Coming Soon: Exhaust, Intake, Gears
96 Jeep Cherokee Sport 2DR
2" Lift, Rancho 5000 Shocks, 31x10.5x15 BFG AT, M/T Classic, Rusty's Air Tube, K&N Filter, Scream'n Demon Coil, Jeepers Creepers Bored Out Throttle Body, Banks Header, Hunsacker Racing Seats, Hurst Shifter, Husky Floor Liners