The recommendation of a 10W30 motor oil is a good one and will make he difference between burning oil and not burning oil IF the car at present is not burning oil.
But once the thing starts burning oil, a symptom of wear, noting will solve it, the engine is worn out.
A condition that can be directed at the recommended use of a 5W20 motor oil which was really too thin to use long term unless the daily temperature was well under freezing.
A problem that is no longer restricted to the early Saturns but seems to prevail on or with the new cars made today and driven hard using that light of an oil.

White smoke is not a sign of oil burning, it's a sign of oil and water mixing. You REALLY don't ever want to see that coming from your exhaust pipe!

I started out looking for assistance with an EGR valve, but now I find myself concerned if my new car is going to explode at any minute. Just went out and checked the oil, again. I have just over 400 miles on since purchase, and oil is still on the full mark

As with any new purchase you need to monitor oil use. Once you know what you have you can relax. I have a Lincoln Navigator and I don't have to open the hood between oil changes. I also have a hotrod Geo Metro that uses a quart every 1500 miles. It doesn't matter as long as you know, many cars get run out of oil and they turn to crap pretty fast.

Of course. Just the way they kept on the oil burning thing, I was getting the impression that it is endemic to the Saturn S-series engine, to the point where I was wondering if I needed to be under the hood before I started it every day. (Or worse, considering how to offload it before it became a money pit)

My intention in bringing the whole thing up was to make you, as a "new to you" Saturn owner, aware of a condition that commonly occurs one the s car engines due to insufficient lubrication using 5w30. Since we dont know if the previous owner disclosed any such info, I wanted you to err on the side of caution until you know what you inherited.

At one point my 95SC2 was using 6 QTS of synthetic oil per 3k mi; more if I used Dino oil. Still drove like a champ and somehow passed nj emissions fair n square.

That's why I emphasized the importance of monitoring oil level/consumption from the very start so you find out what you have going on and don't punch a hole in the block in 2k mi because you weren't watching the oil.

Paranoia right after a vehicle purchase is good if you ask me; it gets you to focus on evaluating the health of all subsystems of the car and lets you prioritize any required remediation. You don't know the past history so you take nothing for granted, learn as you go, and all will be fine as long as you keep up w the maintenance issues.

You AND the car will be fine...

It's true that I don't know the history. The car had a mechanical inspection prior to purchase, so I hope any big, bad stuff would have been caught there. I had been monitoring the fluid levels. I've had a lot of cars (My Saturn is lucky 13), so I know the drill. I hadn't known they had issues with the lubrication. I will remember that when oil change time comes around

I replaced my EGR valve within the past year. I saw that you said you found it within the $135 area. Take some time if you have it and search thoroughly! I think I found mine for way less when I replaced it. It was OEM spec but by a different name. I have also found that often parts like Delco will be right up there on most sites, but you can find them cheaper. I just replaced my IAC valve. I originally found it was going to be between $150-$195 online but then after some extensive searching, found it for around $70 (still Delco). Good Luck!

where did you experience said miracle?

I believe I found it on amazon (the iac valve). I know I also found the egr for less as well but can't find the old receipt