I was looking at the Mobil1 web site yesterday pondering changing over to synthetic. It seems that the 0W30 is not optimal for where you live. I think it is more for very cold regions since it claims to flow very easily. Living in Houston where is pretty warm year around, I'm using 20-50Castrol. On the Mobil web, they show the insides of a BMW that went 1mm miles. THe claim is that the engine parts that they show layed out on the table were up tto the original specifications; pretty good marketing... I'm especially suseptible to stuff like that!
Lee; I'm curious what oil your using for your 500E. I'm considering switching to Mobil 1 15-50.
In general, I'm getting the picture that regular oil changes, just like our dads taught us, is key... the rest sort-of fits in the religion and politics category!