The oil warning light refers to oil pressure, not level. You're supposed to stop the engine immediately to prevent damage when that light turns on. With continued driving the bearings will be the first things to scrub away. That results in excessive clearance and loss of the ability to build oil pressure. With little oil pressure the hydraulic lifters or lash adjusters will bleed down causing the valve train to make those clicking noises.
You'll need to get a mechanic involved to see if serious damage has occurred already to the engine, and if so, if it can be saved or it will need to be rebuilt. The initial cause of the low pressure must determined. It could have been caused by low oil level, failure of the oil pump, normal bearing wear due to high mileage, or lack of oil changes at the recommended intervals.
Tuesday, October 29th, 2013 AT 4:01 PM