What type of oil do I use? 2002 Elantra.
 

For the 2002-2005 Hyundai Elantra.

Some people say to use 5w-20 and some say 5w-30.

Which is it?

And where is the oil filter in that car?

I cannot see it from the top of the engine. Is it somewhere behind the engine, or to the side, or in front of the engine by the front bumper?

Please answer asap.

The oil filter is located underneath, on the passinger side. It's a good idea to put your car on ramps to change the oil.

As to what oil to use, it's more a question of what you are doing with the car. Thinner oil is a little better in cold weather, but it doesn't work as well in hot weather. 5w 30 is already pretty thin. Thicker oil is better if you drive the car hard, but thinner is fine if you drive normal.

Amsoil 5w-30
 

I use Amsoil 5w-30 in both my Elantra's and change it once a year whether it needs it or not.