ya its better to stick to min 10 than 5... check x-javan shop... i am using yamalube semisynthetic for my bike... its 15W40(which is recommended for R15)... i am using the same oil(the recomended grade for FZ is 20W40 mineral oil)... my personal opinion is to go for any semi syn. coz its really good and more than enough for our bikes... if you have the moolah go for the FS...

otherwise stick to any semi syn.
nee yamalube semi syn. oil onnu use cheythu nokku... coz FZ's service interval is 3000kms... so when i used the mineral oil, it gets to change its property/sticky feel around 1500kms... the semi syn. version is more good almost until 3000kms...
if pulsar's grade is xW
40 then my opinion is to go for yamalube semi syn. which is a good one. the gear and engine is smooth and relaxed in long rides(TVM-Thrissur trips

) also...