I just picked up a Cub Cadet 3240 with a 22HP Kohler Command to use primarily to push snow. However, I want to use an oil that also be good in the summer should I choose to mow with it. It calls for 10W-30 or 10W-40 above 32* and 5w30 or 5W-40 below 32*. I'm thinking a full synthetic 5W-40 would be good year round...something like Rotella T6 5W-40. What are your thoughts?