I second the 5W-30 recommendation. Most people mistakenly believe that higher mileage motors need heavier, thicker oil, which is not the case. I also firmly believe in synthetics, especially since our cars run at higher temps. Synthetic performs much better at high temp than dino oil, it has much more uniform particle sizes, and it is less reactive. If you have ever sent heavy equipment and machinery oil samples to be analyzed, you know what I am talking about. Synthetics may "leak" more than conventional oil, but this is because they do a better job lubricating and the particle size is more uniform (and usually smaller). I can live with some extra drips to offset the added protection.
EDIT: I also use 0W-20 full synthetic in my Subaru with 130,000 miles and change the oil every 7500 miles even though it looks very clean. Compression, emmissions, and performance of this motor are still outstanding. I've run other cars well over 300,000 miles on lightweight synthetic oils. Hell, even when I get rid of them the motors are still good.