That happened at my house also. It was like something happened to the oil in it.
something happened alright, the oil turned rancid.
Was your peanut butter in a plastic jar or in a glass jar? Mine was the larger size in plastic.
Oil will not last very long. It’s a problem for long term storage. Lard will last considerably longer if it’s in cans with sealed lids (not that pull off aluminum crap), but it’s not “heart healthy”.
I have been doing some research on getting oil from nuts, since we have several nut trees that produce well on our property. I am also experimenting with sunflowers to see if I can learn to grow and produce oil from them.
I think it would be neat to be able to do it, and it could be useful in a long term hard times scenario.