I've read some posts about people that still used oils that were going bad. And it actually made good soap, I remember one issue was tracing faster because as the oil breaks down you get more free fatty acids which saponify immediately when lye is added.
You could also try cleaning it. I got the method from here, you add an equal amount of water as the amount of oil you have into a pot, add 10% salt (% of water) and bring to a boil. Agitate the oil with the water well, and then set aside for the oil to separate out. Remove the oil, discard the dirty water. I used this after I burnt some coconut oil with coffee. I repeated it 3 times, and after the second time the burnt coffee smell was completely gone, and the color of the oil changed drastically just after the first time.