What can happen if you use different antifreeze.

Corrosion of metal parts. Acid buildup from normal seepage of combustion gases. Normally the problems come from mixing different types that are not compatible. There are some on the market now that advertise they can be mixed with any other type but I don't trust that. Mostly it's the red Dex-Cool, (Dex-Mud) used in GM vehicles that causes a lot of trouble and we want gone. If you flushed your entire cooling system, then put in one type of wrong coolant, I don't think I'd panic. The main reason we want the stuff changed every two years is that's about when the anti-corrosive and water pump lubricant additives wear out.