Jimm 7/8/2013Several possibilities; faulty oil pressure switch (located near the engine oil filter), faulty / corroded wiring or connection at the pressure switch, faulty oil light (loose connection).
Check the many on-line auto parts sources, such as; www.partstrain.com, www.partsgeek.com, www.carpartswarehouse.com, or www.rockauto.com for the replacement parts.
For example, they (RockAuto) list the oil pressure switch from around $7.60 for your vehicle. Before replacing any parts - first check the switch and wiring conditions.
Bill 7/8/2013If this is dirty oil change, then if problem persists do as Jimm has recommended.
John's Auto Repair 7/9/2013The other possibility is low oil pressure. the oil light comes on when there is less than 5 PSI of
oil pressure. If pressure switch doesn't fix it then have the pressure checked with a positive
gauge ( mechanical gauge ).