I would appreciate some input. Because of the high cost of Mobile 1 synthetic, I stock up when it is on sale. I have some, still in the plastic bottles that is maybe three years old. Is there a shelf life for unused oil? I'm sure I should rotate the containers but does anyone know if it can go bad if it is kept too long?

 

The concensus suspect on Google is 5-10 years. So you're good.

 

Five years seems to be the general recommendation:
Oil shelf life | Passenger Car Motor Oil (PCMO) - Gasoline Cars/Pickups/Vans/SUVs | Bob Is The Oil Guy

I've also wondered about oil shelf life, since I maintain 5 vehicles and add to my stash only when there are sales. Here's what my current stockpile looks like ( I know, it's a disease...)