Trust me after all this work I wanted to go by the book with 10-30 in it and use HTO additive. I couldn't find any at all, it's been discontinued for years. One place online had a quart listed for $400 bucks. I spoke with two case dealers, they both said the new oil does not need the additive and they both recommended the 15w-40 for this exact machine. The good thing I guess is we don't use it when its real cold out, almost always above freezing at least.
