That depends on which engine is in the mower. If it is a Briggs it takes SAE 30. If it is a Kohler it usually takes 10W-30.
30 wt
5w30
10w-30w is fine
sae 30
SAE 10w30 full synthetic.
Agear drive will use 90 wt whereas a hydro will use 10W30.
Any straight 30 weight should do.
Whenever you purchase a push mower you have to realize that it needs a higher grade oil. You should use a higher standard type of oil.
The oil to use for the 26hp Kohler motor on a Craftsman garden tractor will depend on the temperature outside. Use a 10-30 blend in the summer and a 5-30 blend in the winter months. The brand of oil does not matter as long as it is not a synthetic blend.
Two stroke oil. Preferably high quality or synthetic, 40:1 ratio.
SAE 30wt
Use heavy duty 10w40 oil and depends if you had fully synthetic or not. I use Delo fully syn. 10w40 that's whats reccomended