This afternoon I noticed 10w30 RT6 at my local Walmart. They also had 5w-40 but were out of 15w40. Would a 10w30 synthetic HDEO be a one and done for all of my OPE in SE Pennsylvania, including the snowblower? At this point I have both 10w30 HM and 15w40 RT6 on hand to cover the next two years, but I am still searching for that one size fits all OPE oil.