Which oil?
 

I just got a new 2008 Entourage. I plan on changing oil at 1500 miles, then again at 1500 miles using the recommended oil in the manual both times (5w-30, I believe). After that, I would either do routine oil changes every 3k with the same oil, orshould I switch it to a synthetic at the 6k mark and continue with synthetic after that every 5k?

Which oil?
 

:)

Look in your owners manual and see if Hyundai doesn't recommend 5W-20W?
If they do, that is what you should use!

Changing early is a good idea and I wish I had done that instead of waiting until 3,500.
I had my old oil analyzed and found it to be rather dirty mostly from the breaking-in
plus leftover junk from the original castings etc., so changing the
original oil anytime after the first 1000 miles is a good idea IMHO.

Irecommend Mobil 1 5W-20, but changing it every 5K miles is a waste of money.
At least go to the factory recommended 7.5K although I believe that 10K is a better idea.

Good luck
If you want to spend $22.50, you too can have your old oil analyzed and go from there.