I have about 345 miles on my 1800 so far and I'm getting ready to change the oil and rear drive fluid. I plan to buy the fluids at Advanced Auto or Auto Zone, so can someone tell me exactly what brand and weight of each I should buy? I'd rather not go to the dealer and get raped for GN4 and other high dollar fluids....i've heard alot of people talking about using regular old Mobile 10W40 or something like that. Any help appreciated. Thanks.