hello,

what is the shelf life of sealed motor oil container of 5 litres or whatever?

Generally two to five years.Make sure that oil meets the specification requirements,by sending a sample to an oil analysis lab,before use.

The temperature is also playing a vital role in the shelf life of the oil.

I've heard all kinds of numbers for this. Two years seems awfully short. Five years looks like a good conservative estimate, but ten years probably is workable when properly stored (avoid freezing temperatures and high heat, so no garage storage). I'd try to stay within roughly 5 years. If you buy a new car and have 5 year old oil, it will not meet spec (e.g., SJ or SL oil and manufacturer specifys SM).