However, if you don't have the owner's manual, a common recommendation for many 1996 Ford Explorer engines is 5W-30 conventional or synthetic oil. But again, this is not a guarantee and should be confirmed by checking your owner's manual or a reliable online resource that specifies the engine.
When you look up information online, be sure to specify the engine size (e.g., 4.0L V6, 4.0L SOHC V6) to get the most accurate information.