My owners manual says to use sae 30 oil in my craftsman 20.5 hp riding mower. I have some sae 10w 30 oil in my garage. Would it be safe to use the sae 10w 30?

I don't see any problem with it I have used 10-30 oil in my lawn tractors for years and had no trouble. Maybe someone else will disagree but the oldest one has been running since 1974(its true). The 74 I have is also a craftsman. GOOD LUCK, AC

Hi,
No problem as long as you do as every manual tells you and some do; "check oil every time before starting." 10W30 actually has a broader operating temperature range, but can be consumed a bit more. 5W30 is a no-no as it can be consumed a four times the rate especailly if loaded when not at full throttle.
Peace,
Clarke