A good option for the turbo engine that you might not be aware of is Mobil 1's 5W/40 grade. Originally marketed for heavy duty turbo-diesel engines as Mobil Delvac 1, they now also sell it as Mobil 1 Truck & SUV. I've used the former both professionally and personally for over 10 years and now buy the T&S oil from Wal-Mart for my Cruiser. I know a lot of guys still change their oil every 3,000 miles, but I go to around 5,000 with the synthetic product. Mobil says that you can take Mobil 1 to 15,000(and that's the interval we use on our big trucks), but I want to keep the inside of my engine a little cleaner and am still willing to spend the extra money to do it. I'm certain that the oil won't break down, but I'm less comfortable with the longevity of the detergent additive package.
Remember that all the advice here is free and should be taken for what it's worth. So ultimately, take what you've learned here, and do what you're comfortable with. I hope that you enjoy your Cruiser as much as I have mine!
