I feel certain you could. Oil never goes bad. It just loses its additive effectiveness. I had a case of 5x20 I got for Kitty's Escape a while back that was "remanufactured" oil. There's a place in Macon that does it. Perfectly fine. The price was pretty close to what I can get it new, so I didn't bother again. They offer it really cheap in larger quantities.
Remanufactured is really what it says. Pretty much a cracking tower process on a smaller scale that removes all impurities. Re refined would be the term. The base oil stock stays good and a new additive package is mixed in.
Years ago the Castrol GTX oil had a very distinctive odour. I got sent up to one of the if not first facilities at Fort McMurray for 2 weeks. They refined oil and used it in their equipement. Same distinctive odour. The used oils got recycled and run through the refining process again.
