Well, I can only speak from personal experience. My Saturn also uses nylon tensioner guides for the chain.
I ran Mobil 1 5w-30 for the first 103,000 miles, then switched to 10w-40 and 5w-40 Amsoil, Redline, or Delvac 1 (mostly Delvac 1) through the current 190,000 mile mark.
The chains on these cars, especially single overhead cam engines like mine, are known to signal their impending doom quite clearly by making your engine sound like a diesel. This hasn't happened to me yet, and I don't intend to do anything about the chain until that happens.
So, in my experience, if you run a quality synthetic oil of whatever weight of your choosing, that will do best for the chain. The worst thing that you can do for a chain is let the oil level drop (at least that's the case with Saturns). Keep the oil topped up, and keep clean oil in there and the chain will likely last a long time.
Incidentally, someone somewhere recently posted a link to an article about significantly reduced timing chain stretch with Delvac 1. You might want to look that up.