Actually, that probably would not make the filling authentic either. My only goal would be to fool the grandkids. Some guy got 15 years behind bars for selling the filling recipe to the Chinese for $28 million.
https://www.eatthis.com/the-worlds-8-most-addictive-foods/
Until 1997 the filling was made out of pig lard, sugar and some chemicals, but these days it is most likely “sugar, palm and/or canola oil, and high fructose corn syrup.
It turns out that according to a study using rats that Oreos are more addictive than Cocaine and Morphine.
https://www.eatthis.com/the-worlds-8-most-addictive-foods/
Right, in 1997 they switched from lard to partially hydrogenated vegetable oil, aka vegetable shortening. They used hydrogenated oil because it has roughly the same consistency as lard. That’s because hydrogenated oil is saturated making it solid or semi-solid at room temperature. If the current OREO ingredient list doesn’t show hydrogenated oil, it’s because they’ve replaced it with palm oil which is naturally saturated and has the same consistency as lard or hydrogenated oil. I doubt you would fool the grandkids if you made the filling with regular liquid vegetable oil. I suspect it wouldn’t have the right creamy texture.