no, run 5w30 all year. 5w30 is always better than 10w30, oil is too THICK, not too thin. 10w30 would work, but just not as well as
5w30.
also, NAPA synthetic is on sale this month for $3.00 a quart, so buy up a stash of NAPA, and forget ST. They jacked up ST prices, and then conveniently "forgot" to lower them, once they realized how much bonus was needed for the CEO. so go out and stock up on NAPA, which is Ashland (Valvoline) oil.