fully synthetic in a guzzi is a bit of an overkill. synthetics are great for modern engines with super tight tolerances, but old aircooled bruisers like the guzzi, or beemer boxer arent really designed for such super thin lubrication. i always ran my beemer on mineral oil, after all, it was all there was when it was designed and sold, and pc plod ran legions of aircooled twins on mineral oil for a cumulative total that must be in the tens of millions of miles. synthetic oils in older engines tended to leak out more, (when i tried running the bmw on some fully synthetic oil i was gifted, it leaked and smoked like a good un, although it did smell nice, same issue with the katana i was at that time running, changed the nature of the bike totally when i ran it on gtx again)
the reality is that synthetics are capable of being left in an engine for an extended length of time, after all, if you only need to adjust your valve shims every 20k miles, its a bit of a pain to need to drop the oil every 5k. sythetics were designed for high revs and high pressure lean running high temp engine environments. i dont think the guzzi will be harmed one bit by running on gtx or similar, in fact i use supermarket own brand oil in my aircooled engines to this day. except for the bsa, that gets the old mineral oil i drain from the beemer....
