Thanks. My Autozone (a real dump) didn't even have the signs up. I brought 6 quarts to the counter and asked if there was a buy 5 get one. They guy didn't have any idea. He rang up the bottles and sure enough the register subtracted the last one and noted the sale.
I also bought 4 quarts of 5W30 Superflo and got the fifth bottle free. I figured I would use the Superflo with Auto-RX or flush after Auto-RX or in one of the many "free" oil changes I do for relatives.
Thanks for tipping me off on the free bottle of Syntec