My son and I have decided to do our own maintenance work on our respective Jeeps. I have a 2010 JK and he has a 2003 TJ. For our next oil/fluid changes we are switching to synthetic, probably Amsoil. My JK has 33,914 miles on it. I bought it April 2012 with 9100 miles on it. In a little over 3 years, I have put 24,814 miles on it or 8,271 miles per year. No off roading or towing. It is my daily driver with mainly local driving. In saying all of this, do I need to change the differential fluid, transfer case fluid or manual transmission fluid at this point? Dealer doesn't think it is necessary.