My Kubota Owners Manual states using an engine oil that meets: API Service Classification CD, CE, or CF
For temps above 25 C (77 F): SAE 30W, SAE 10W-30 or 10W - 40
Temps 0 to 25 C (32 F to 77F): SAE 20W, SAE 10W-30 or 10W-40
Temps Below 0C: SAE 10W, SAE 10W-30 or 10W-40.