ghstudio wrote: I can't imagine actually needing to replace the transmission or differential fluid or all belts after only 30K miles.
All belts at 30k ... no! Probably better to do them around 60k miles - as long as a check of the belts does not show any wear or fraying.
Transmission fluid ... most definitely yes! I strongly recommend doing the transmission fluid flush every 30k miles if you want longevity out of the Nissan/Infiniti transmissions!
Differential fluid change is easy enough and cheap enough that doing it at 30k miles will not hurt. Since the differential is not an environment where heating occurs (like the transmission or motor), this is less of a concern than those other fluids.
ghstudio wrote:Coolant is probably a good idea as well as rotating and perhaps rebalancing the tires but frankly I would just let the OEM tires wear themselves out and use the money you saved to buy good tires.
Doing the rotation (you can do this yourself - just get a torque wrench from Sears to set the lug nuts to the recommend value) makes the wear more even, and then the set can go longer. Since I way prefer to replace all four tires at the same time (not each axle separately) so that I can have a choice of different tires if I want, this is a better way to go.
Finally, I am a believer in re-balancing tires every 3k to 4k miles. It makes the car ride smoother, brake better without vibration (far more often the cause of braking vibration than "warped rotors), etc.
Z