That oil warning light is an oil pressure light. Once that comes on it means that you have a low oil pressure condition inside the engine, which can be a major problem, even if its for a second or two.
Once I top it up it never came back on, I didn't get a check engine light at all when I owned it. But recently I sold it because it was giving me acceleration issues. Could have been something as dumb as a spark plug or coil plug, but couldn't afford to fix it so I had no choice but to sell it.
