All oil will eventually go rancid, IE, oxidize.

Saturated fats oxidize slower than unsaturated fats, so 'crisco'-like oils will go rancid much slower.

You want to keep the oil water-free, out of the light, and in a well sealed container with as little head-space as possible. Water, light, and air will all accellerate the oxidation process.

If your oil smells like linseed oil, its rancid, and shouldn't be used.

There are so many variables that it can be very hard to give any reasonable 'shelf life' numbers, but I'd say it can vary from a few months to a few years, depending on the oil, its water content, and how it is being stored.

peace,
sam

PS The same storage guidelines go for biodiesel too.

__________________
"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)