Dear PT. ,my manual calls for 5w-20 or 5w-30 below -14f, 10w-30 +50 to-4,20w-40 or 20w-50 +86 to +5, 15w-40 & 15w-50 +86 to +5, 10w-40or 15w-50 for +86f to -4f. This winter in Colorado hi country, I am running 10w-40, by july will have the 15w-50. Trust this will answer you oil question, Regards, Moonshine,(Don't ask)