Once you open a container of mineral oil, it is best to use it up within 6-12 months for optimal performance. Generally, when sealed and unopened, refinery-grade mineral oils can last around 5 years before experiencing degradation due to oxidation and hydrolysis reactions. Even then, the oil may still be physically stable enough to provide lubrication on mechanical parts but its chemical properties will have deteriorated appreciably by that time.
In terms of safety and efficacy considerations, there are some applications where using old mineral oil should not be used regardless of its physical condition or remaining shelf life. For example, if you are using mineral oils as a component in consumer products that require FDA approval such as food processing equipment; the food industry regulation usually states that all fluids used must be fresh (under 12 months after opening) even though they may appear physically fine on inspection. In highly critical engineering environments with demanding safety requirements like aviation hydraulic systems; again most regulations would ask only for resource material less than 12 months old regardless of physical condition being satisfactory otherwise.
The shelf life criteria vary depending on conditions kept too - exposure to light intensity or temperature changes can exponentially reduce the lifespan whereas dark places with moderate temperatures will help extend its lifetime noticeably longer than expected considering other factors remain unchanged. Therefore if you store your opened bottle of mineral oil properly in an airtight dark place at room temperature (or lower) - it should stay usable far beyond 12 month period safely provided that other factors remain favorable to consistent performance quality throughout its usage period over time too!