could be ideal, unless in cold conditions. I doubt that the sae30 recommendations are sooo cloes tolerance that the 40 is waay off. never noticed anyways. What I do know however is that those HDEO is, well; Heavy duty, compared to the cheapest 10-30s, the 15w40 are really well made.
Having said that, I rund 0w30 in the outside stored snow blower, and any oil between 0w30 and 15w40 in summer use ope