2005 Toyota Prius: What is the oil type and capacity?

EacH2005 Toyota Prius comes with the same 1.5L 4Cylinder engine with engine code 1NZ-FXE. This engine requires the use of 3.9 quarts of SAE 5W-30 full synthetic motor oil. In particularly cold temperatures, SAE 0W-30 is recommended. In the absence of the above, it's possible to use SAE 5W-40 in a pinch, though this is not recommended. The reason is that when You use an oil with a higher weight, You're actually using a thicker and more viscous substance. This introduces friction, which can prematurely wear Your engine over time. This can and likely will lead to premature engine failure, so it's always best to go with the manufacturer's recommended oil with the lowest weight, even if it costs a bit more per change.