Has anyone used AMSOIL synthetic products. I would like to know if there any concerns in using their engine, differential, transfer case oils and air and oil filters

Amsoil is a VERY good lubricant. I used the synthetic motor oil in my Jeep until very recently (switched to conventional oil due to higher mileage). I use the 100:1 TCW3 in my boat. When I worked at a motorcycle/jetski shop we used amsoil in everything (4 wheelers, Harleys, Jetskis, shop vehichles) I would recomend it as long as it is the same weight and type fluid. What kind of Jeep do you have?

1999 Grand Cherokee Ltd., 4.7, Quadra-Drive

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 www.wjjepp.com