Engine Knocking Noise problems of the 2011 Kia Motor RIO

I'm really not sure what's wrong with it bit this is way happened. I was driving to workfrom lunch wasn't having any problems then all of a sudden the engine light stayed flashing. In the 4 mins that followed my car started loosing power so I pulled over to a gas station once I stopped the car I heard a knocking sounds and then the car shut off. There was oil, it wasn't black, it did not have white spots and there was no smoke v of any color coming from the hood or tailpipe. What was weird was that the antifreeze reservoir was completely bone dry. I had a oil change and fluids check and topped off the two months before and had checked the fluids myself the month before after my spark plugs were change. Needless to say finding no antifreeze in the reservoir was a little bit confusing. Had 3 mechanics look at it and they all said if the ass no oil they would have said the rod was thrown or piston broken but I need to pay someone to take the top off the engine to even get to where people guessing the problem is. Worse thing is the car is only 3 years old and maintenance is done on it so why I'm I having engine problems?.