Mineral oils are used in many Anti-Ageing and Cosmetic products to "fill them out", however there is many mixed reports about the effects of mineral oil on the skin. The benefits to mineral oils is cheap, fragrance free and colourless. It doesn't oxidise and can easily be kept for a long time. However the down side to mineral oil is that it forms a film across your skin in a similar way to how it would feel having cling film on your skin. This will block the pores, trap dirt and bacteria into your skin and prevent the action of beneficial ingredients within the products you buy. Hydration of the skin is key to keeping your youthful looks and so the cling film effect prevents your skin from absorbing moisture as it naturally would. Mineral oils are also thought to slow down cell renewal, resutling in premature ageing of your skin. So we are buying anti ageing products, that actually age us.
My advise would be to find products that are free from mineral oils, there are plenty alternatives.
Mineral oils go by other names such as Paraffin and Petroleum Jelly.