Saturn is owned by GM but they are their own system, totally outside the normal chain of command, so I have no idea what they do. I can't even cut a key for a Saturn much less look up a part. I'd expect the have a tank full of "universal" 5w30 SM oil.
You don't understand, they do this because it works. On this board we all obscess about oil and maintenance and sort of expect everyone else to, but they don't. Right now there are hundreds of thousands of vehicles out there driving millions of miles on the "wrong" oil. And they're doing quite well, thank you very much. Do ours do better? Hopefully. But oil and cars are so good now in most cases it just doesn't matter. I know, tell that to the folks with Chrysler and Toyota sludge monsters, there are exceptions.
Two perfect examples. My '01 Hyundai Accent 1.5 owner's manual calls for 10w30 or 10w40 oil. I've run either Supertech Syn 5w30, or TropArctic 5w30 in it for over 50K, it had 37K on it when I got it, it's smooth, quiet, runs like new and gets better highway MPG than it's original rating. Too bad I'm using the "wrong" oil. My brother just turned in his '89 Ford Bronco company truck (Bell Telephone, the cheapest company in the world when it comes to vehicles) with over 300K on it. The private garage he had to take it to put 5W30 in it ever since it was available, the owner of the shop went to a seminar and really believed it was best, even in his own car. The body was rusted, the manual trans had been rebuilt 4-5 times, and the 302 leaked oil from several places, but it still ran great.
I too change my own even though I work at a dealership. I guess I'm just too cheap and like doing it myself too much.
Just for the record, we only have one tank, we don't sell enough of the specialty oils to buy them in bulk. And we're getting screwed on them. We pay more for Mobil-1 and Delvac than what the public can buy them for at Walmart. That gets back to my earlier comment about the front end of the dealership not wanting problems in the back. We just use the GM contract supplier. Shoot, the Corvette owners are mostly clueless anyway, they expect stuff to cost too much.