Mobil 1. it's been around longer than most of the others combined.
I use it in all my vehicles AFTER they have a good 5,000+ on them on normal good quality oil. Thats the most important thing to remember when using a good syn oil. It lubricates too good to allow the engine to break in.
After 25,000 miles in the car (10,000 in my bike) I drain it and save it in the old bottles to use it in the lawnmower and other stationary engined devices I have. (generator which has 20,000+ hours on it and still doesnt use a drop of oil!, and a 8HP air compressor.)
Synthetic oil only turns black, it doesn't lose any of it's lubrication qualities. If it's been used in a decent engine with a good filter there is really no need ever to change the oil, just the filter. Why muck up the enviorment needlessly just because you don't like the color of your oil?