My 50 hr service is due. Have all the filters now looking for the correct oil. Owners manual says 10-30 for -4 to +86, and 5-30 for -22 to +86. and 15-40 for +5 to 104 Here in upstate NY there are multiple days its below -4 so I figure to use 5-40 Syn to cover every base, and as it seems 5-30...