Matt,
I own a different brand tractor than yours. My owners manual has a lubrication table in it listing various oils and brands. It lists weight oils as well as multi weights. My recommended oil is 15W40 but other weights may be used based on ambient temperatures.
10W-30 or 15W-40 when ambient temps range from -4 deg.F up through 86 deg F (-20 to +30 deg C).
5W20 when ambient temps is 14 deg.F or (-10C), and varies very little from this.
20W-40 when ambient temps are 86 deg F (30 deg C) and above.
The recommended brands and weight for mine are listed as follows:
Citgo Citguard 500 15W40
Exxon XD3Extra 15W40
Chevron Delo 400 15W40
Mobil Delvac 1300 15W40
Shell Rotella T 15W40
Texaco Ursa Super Plus 15W40
George