what oil should i use!!!!!

[cable tie]

well im one not to turn a bargain down and was offered 3 x 4ltr tubs castrol power 1 10w40 fully synthetic for £45 and 3 genuine yamaha filters for £15, i know some peeps say fully syn is waisted on the fazer however at that price i thought its too good to turn down, so ive got enougth for 4 oil changes .