I have a John Deere 717A Z-Trak that specifies a 15W 40 synthetic blend oil, SG or better, for the hydraulic oil. Other than Amsoil or the Deere oil, is there any other compatible oil readily available at the store?
Schaeffers makes an excellent 15W-40 blend that is priced right as well. Call or PM "salesrep" (Mark) for excellent service. He is the site sponsor here for Schaeffers. Their full syn 5W-40 would work well, too.
Ok, now I see where you specified readily available at the store. There are probably some local Schaeffers reps in your area that you could look up online or call the main office. Otherwise I would just use some straight Rotella 5W-40 synthetic which would work great year round.
Either way, be extra careful to determine the correct fluid. JD is VERY prone to making mistakes in their owner's manuals.....I know from experience with lots of JD equipment at my workplace.
One guy at lawnsite.com used Amsoil 10W40 in his 717A.