What type of oil does a 2005 Mitsubishi Lancer use?

15w-20 is the going rate for Mitsu 4-cylinder engines. You can get away with 10w-30 in most climates, but I tend to stick to what the manufacturer tells me.
2005 Lancer ES 2.0L, 4G94 Engine The ONLY two oil grades that are to be used with this engine are 5W30, 5W20 (colder temperatures: 100 degrees F and colder) and 10W30 (warmer temperatures: 0 degrees F and warmer).