What weight oil should I use in my 2002 honda vtx 1800 motorcycle?

10w40 gn4 . if you go syn , it will smooth out the noisy shifting !What weight oil should I use in my 2002 honda vtx 1800 motorcycle?
';Use only high detergent, premium quality motor oil certified to meet API Service Classification SF or SG.'; That's straight out of the owners manual.





Any motorcycle oil will meet these qualifications. Also the ';Autozone'; brand motor oil meets these as well and it's only like $2.50 a quart.





I use 10w/40 during the cooler months and 20w/50 in the summer.What weight oil should I use in my 2002 honda vtx 1800 motorcycle?
10-40

vincent