This is just a general interest question and may seem stupid to knowledgeable people. However, I was wondering if motor oil has a shelf life.

I have heard everything from a few years to indefinite (if properly stored). Noria has an article on it that shows how varied the answers are to this question. I store my oil in the cellar which ranges from 40F to 70F. Want to avoid freezing and very hot temps. I have enough oil stocked to last about three years and am confident it will last well over that.

If the can is never opened, it's probably airtight and protected against oxidation (there's always some oxidation).

When opened and closed the oxidationlevel can be higher.

Furthermore: avoid sunlight and temperature differences like TallPaul already mentioned.
All the new synthetic (long life) engine oils, already have better 'storage' capacities, as they have to stay in your engine for more than two years sometimes...

Hope this helps you out a bit...

Most manufacturers will give a shelf life to their oils. Mostly due to additive settling. But a lot of "experts" say that an oil in a sealed container will last indefinately. Just make sure the container is agitated before use.
Personally, I believe oil properly stored will have an extended life but there are a lot of factors which will effect the oils properties.