How long does Peanut Oil keep In my case its still sealed in the container, and http://www.eatbydate.com/other/condiments/how-long-does-oil-last/ claims 3 years (unopened) / 2 years (opened) but that doesnt seem to jive with experience.

Any have more data on lifespan of Peanut Oil?
This answer says that unopened vegetable oil lasts for about 6 months, opened 1-3 months (source: Julie Garden-Robinson, North Dakota State University, FN-579 Food Storage Guide). This corresponds to your experience.