Well,I would opt for Non-detergent in the tranny.Just `cause I'm not too familiar with Garellis.I use detergent 10w30 Exxon synthetic in my Minarelli(has a wet clutch) in the winter and have had no problems.But if that Garelli has that rubber washer between it's clutch,I'd stick to non-detergent 20 in winter and 30 in spring and summer.That won't swell the rubber.There are better Garelli people than me on this forum if they'll answer you.There's also a link to Garelli on this site,but I don't know vwhat it covers.Just go to `resources',then `links',and scroll down to the Garelli site listed.A trick I use in severe weather is to hang a `trouble light' next the tranny a couple hours before I take a ride,making sure there's no chance of gas leaking onto it,of course.This warms the tranny and makes for easyt startups.