0w-40 if you live in the north. 10w-40 or 15w-40 if you live in the south. amsoil is the best. valvoline or mobil 1 is good. dont ever use pennzoil

 

So can i run 0w-40 or -w30 all year around or just during the winter?

 

you can run it all year round. the first number indicates the oil's viscosity at cold temp and the second number indicates the oil's viscosity at warm temp. the lower the weight the thinner the oil will be. You want a thin oil in colder temps so it can flow better, but a thicker oil will help cool the engine down better at higher temps and protect again wearing of internals. And as a general rule of thumb, you want the least amount of difference between the 2 numbers without going outside of the temperature demands of your environment and application.

So if you live in a cold environment (sub-freezing point) you want a 0w or 5w oil for the cold weight. If you live in a warmer environment you don't want a really thin oil (since it won't cool the engine as well and will cause more wear) so a 10w or 15w for the cold weight is better. As for the hot weight, if you just use your car for a daily driver and its pretty much stock a 30w is plenty sufficient. If you like to run your engine hard and/or are pushing lots of power (which generates more heat) a 40w is a better choice.