Can i keep that 3 year old mascara...

Mascara
Shelf Life: Three-six months
Mascaras should always be used fairly quickly once they're opened because they're easily contaminated by the pumping action of the brush. This can force bacteria further into the container where the moist, wet environment is ideal for bacteria to thrive.

* Stick to one and use it regularly so you finish it within a few months. This is far better than alternating between a number of different mascaras, which means you keep them longer and increase the risk of contamination.
* Never add water or other liquid to mascara to keep it from drying out, as this can cause the preservative to become diluted and therefore offer less protection against germs.
* Never share mascara, as this is the most common way to pass on eye infections such as conjunctivitis.
* Don't use the same mascara if you've just had an eye infection, and buy a new one to minimize your chances of the infection coming back.
* Don't use saliva to moisten mascara. The bacteria from your mouth may get into the mascara, which can encourage bacteria to grow and cause infection.
* Always wash your hands before applying mascara to cut down the risk of passing on bacteria with your hands.
* Keep mascara in a clean place. Don't let it come into contact with dust or dirt that may harbor harmful bacteria.
I also recommend not pumping the wand in and out of the tube. It lets air into it, and it goes dry too quickly. SOme people I know say, well, use the old mascara on your brows, but I say...that why there are brow combs, the old mascara can flake into the eyes, and cause irritation and itchy skin.
Mascaras come in a whole range of price categories, so you cant blame price for keeping a mascara forever.