It should be replaced when it begins making a noticeable noise.
Which model Saturn?
Yes Saturn cars have very good gas mileage. They are compact and well made, they have good engineering work behind them that designed a good car with great gas mileage.
You must be talking about a vehicle from space, since there is no such thing as a Nissan Saturn. It's impossible to answer your question as asked.
It is illegal to do so and will void your warranty.
Depends on the year, model, mileage, & condition Saturn you are talking about. Look here to get values: http://www.nadaguides.com/Cars/Saturn
Saturn recommends 5W30. But I put 10W30 in my 2002 Saturn SL2 now that it has higher mileage, and it runs like a gem. I use Quaker State High Mileage (with Slick 50) to give it additional lubrication.
I have a 95 saturn and it cost an average of 300 dollars to get the windshield replaced.
The Saturn S series is an old automobile. Commercials for them were first broadcast in 1992. The line was discontinued in 2003 and replaced by the Saturn Ion.
Saturn does have a model called the Ion.It was a compact car sold between 2003 and 2007 and replaced the Saturn S-Series.
If you're certain that the sound is from the serpentine belt you should check the belt tensioner. A weak tensioner spring will result in slipping and a noisy belt.
Use 10W-30, any brand, pending on mileage