same Jeep i have-- Use 75-140W Synthetic in the differentials-add limited slip to both axles also. Stick with the 5w-30 for the motor. I would consult Amsoil for the correct Tranny fluid and Transfer case fluid- I know Mopar +4 is the only fluid recommended by Jeep for the tranny and Mopar Transfer case lubricant for the transfer case. Good Luck-Check out
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