Saturn had a lot of fit-and-finish issues, but man the S-series was reliable. I had one for 13 years/250,000 miles and barely put more than tires, brakes, and oil into the car.

The oil, though, was interesting. The s-series engine had a design flaw with the oil control piston ring where it would get stuck in its groove due to carbon build-up. The engine would then start burning prodigious amounts of oil — mine burned 1 quart every 500 miles. I put the cheapest oil I could find in as a result and when I did a filter change I’d save the old oil to pour back into the engine (diluted — about 1 qt of old oil and 3 qts of new.). By the time I used up all of the old oil it was time to change filters again.

What I've heard (i.e. this may just be hearsay) was that for much of its history Saturn used engines that had bores with a fairly rough surface finish which resulted in them holding more oil and reducing wear on the bores and rings but at the cost of burning more oil. Sometimes they burned quite a lot of oil as they got old.

GM treated Saturn like a throwaway brand so they used them for a lot of R&D they didn't want to risk "important brands" over and consequently there's a bunch of random Saturn cars that have features that even some new cars don't have. My friend had one from the early 2000s that would vary radio volume with speed and window position.

The rough cylinder bore didn’t help, but the root cause was the design of the bottom ledge of the oil control ring grooves and the lack of proper drainage.

A popular shade tree mechanic fix was to drill drain back holes in the oil control ring groove: https://m.youtube.com/watch?v=UrnblJ8VZtY