Guys, well my Sl2 the transmission blew, Im looking for another car, found a 96/7 Jeep 4Wd automatic. Went from 35Mpg to under 20. Well anyways, It has around 140K miles, I really want to use some kind of synthetic, but being it has so many miles, do not think i will, only because i guess there are know to have to rear main seal leaks... Anyways, this is the first time i have a suv, and have no idea what wt oil to put in it, I dont think its not 5-20/30 as they seem a little thin, How would 10-30/5-40/10-40 do?? again, i may use like ST synthetic, but it takes around 6Qts total.. What is the correct filter size? I dont think i need to worry about an over sized one, and again what would be a good OCI? 3-4K miles on dino 5K on synthetic? Ok so all in all -Best oil, Dino or syn -Best Oil Wt summer/winter -Oil Filter size/number -OCI's Thanks!!