Going to install a new clutch this weekend. New kit does not come with a small pack of grease for the splines and throwout bearing... Is it a big deal? I have a tube of multi-purpose grease (red).. can I use it?

 

doesn't your manual call for molybdenum disulfide grease?

 

^^

Moly grease is for high pressure situations where metal is sliding against metal just as splines do.

Moly grease with high Mos2 content would be the best. Honda moly paste has 20% content which should be your bare minimum.