Walk behind or rider?
It's the engine that determines the oil requirements, not the brand of the deck.
If it's a small HP walk behind, it probably doesn't matter, but I'd use a 10W-30 vs a 5W-30. A lawnmower infers WARMER weather, so you really don't need to worry about having a "thinner" oil for COLD (winter) starting.
Most newer Kohler engines (rider size) specify 10W-30 because of the hydraulic lifters. Too thick of an oil prevents them from pumping up rapidly. That can cause the lifters to beat themselves to death.

ok beautiful thanks bill. yes it is a walk behind. I have part of the opwnbers manual but it mentions the sae30, but i have alot of unused 5w30 around that i will probably never use. much appreciated fred