I've had my JK 2012 since brand new, it has the 3.6 pentastar with 190.000kms. I service it myself after the warranty ran out and I haven't had any issues. I changed the ball joints but I realised they were ok. I change the battery because it was getting lazy to crank... that's it!! the rest has been oils, coolant, bell, spark plugs and tires... it has taken me to Fraser island many times, beach runs at least once per month and glass house mountains playground many times, cairns x3 , Sydney, Melbourne and other places in Queensland and NSW. there is no rust at all and it drives the same as when I picked it up from the dealer. I totally love my jeep. The best thing is that it doesn't need any modifications unless you want to, but I haven't needed a lift kit or lockers or anything (aggressive tires is a must!
service it and the jeep will love you back.