do they have the oil light to let you know it is time to change it?

I'm not sure but you should never go by that. 3 months or 3,000 miles on regular oil or 5/6 months or 5/6000 miles on synthetic oil. Plain and simple. Change the filter with every oil change too.

On most vehicles there is a oil warning light indicating low oil pressure, (bad). Some have a separate indicator for oil life. Without knowing which indicator you are referring to, I would recomend checking the oil level before operating the vehicle. If low, add oil and check for leaks. Once the oil level is good, take it by an auto parts store.. they can tell you for sure what the indicator means.