Ilovemountains

Sometime at least 5 years ago I did a 16 quart flush on my transmission using AAMCO Semi Synthetic ATF that I bought at AutoZone. Id like to flush it again or at the bare minimum drain and fill the pan but I can’t find the same fluid. Does anyone know of a parts store that still carries it or do you see any issue with mixing a different brand of semi synthetic with it or should I just flush the whole system again. The trans fluid is still nice and red but it’s been in there for at least 5 years, I’m not sure if it gets corrosive or not.