Expired vegetable shortening - can I still use?

[Anonymous]

I already dumped it into the batter and everything looks and smells OK. It's about a year beyond the "Best By ___" date.

I can't actually do the taste test the way I might with milk or chicken because to me, all shortening tastes off; kind of like eating corduroy.

Is it possibly rancid? The shortening ingredients are various vegetable oils and preservatives ...