After posting my reply I did a quick search on the subject. I can't find any specific data on it, but the fancier the oil the shorter the shelf life. Some places give basic motor and transmission oils are given a 5 year expiration date, other oils like those fluids used to lessen friction on lathe machines are given a 2 year exipiration date (the are often more watery liquids, and blends of all various substanses). These are all more fancy compunds. Greases can last a long time, still just as fine after more than 10 years, some seem to be very stable. Highly refined mineral oils with no additives (aka good quality sewing machine oil) last a long time in a sealed container proteced from direct sunlight. Exactly when they start to disintegrate I can't find much info on. In soil most of them seem to brake down after 3 weeks, very different from crude oil or petrol.