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.
It is important to use the correct oil to keep a car running properly. The best oil to use for this particular car is 5W-30.
The manufacturer recommends that you use 10W-30 weight oil. 10 W-40 weight oil can be used in high mileage engines.
You don't have to use synthetic oil for your Saturn Vue but synthetic oil is said to lead to better performance by the car. Check out this chart on different types of oil that can be used: http://www.synthetic-motor-oil-change-and-filters.com/best-oil/oil-change-saturn-ion-and-vue-ecotec.php
Engine oil?? 5W30 synthetic is best.
Dexcool
The best type of oil to use in a 2000 Toyota Avalon is 5w20. This provides a good balance of viscosity with the ability to work in most temperatures.
5w30
R134
10W 30 is generally best.
Every person will have a different answer but if you are going to use a conventional oil i prefer Valvoline.
Use only 134-A
CASTROL 10W/40