If GM is willing to stake the life of their engines on their temp/load/RPM algorithm, I'd say it's safe to follow. I'd also still stay on the conservative side of the fence, just for peace of mind. I don't believe there is any point in changing oil every 3k-5k miles though, whenever I've checked my GF's oil at those intervals (I use synthetic) the oil looks pretty clean still. I'm sure the oil has plenty of life left, but it's much harder to check how much life the filter has left in it. For example, Amsoil recommends changing the filter at some interval (which is longer than the recommended change interval for non-synth) and then changing the oil and filter at the next interval. So they're confident that the oil lasts much longer than the filter is good for.