Which oil should I use? The owner's manual says 5W-30, but I bought 10W-30. What is the difference between the two?

 

10w30

First number is viscosity (thickness) when cold. Second number is viscosity when hot.

The owners manual says 10w30 is fine if you don't live in a climate that gets below freezing.

 

Most my driving is very short distances... figure i have just a little extra startup protection...

 

5 is a bit lighter at cold temperature as Eric has pointed out. The second number is the viscosity of the oil at operating temperature. If you live at very cold climates and would like to have that extra protection at start-up go with the 5-30. 10w-30 if you are in warmer climates. Personally, I really don't think it makes that much of a difference, but I use 5w-30 mobil 1 synthetic.

 

Yeah that's what I meant. the "30" is for when the engine is hot (ie operating temp). Okay, so hot might sound like an overheating engine...but you know what I mean. You want extra viscosity when your engine is at operating temp for maximum protection

 

There is Nissan recommendations for Maxima:

5w-20 – high +14 F (-10 C), low – below –22 F (-30 C);
5w-30 – high +59 F (+15 C), low – below –22 F (-30 C);
10w - high +59 F (+15 C), low - -4 F (-20 C);
10w-30, 10w-40, 10w-50 – high – upper +104 F (+40 C), low - -4 F (-20 C);
15w-40, 15w-50 – the same;
20w-20, 20w-40, 20w-50 – high – upper +104 F (+40 C), low +14 F (-10 C);

Hope this table will help you to choose correct viscosity for your climate zone

 

I think I'll just go with 10w-30. It doesn't really go into the negatives here in Seattle. (I'm using Mobil 1 synthetic)