I spoke to the Proietti guys regarding synthetic oils. Interestingly, they swear by it and use it on the 500s and 126s. Everyone has a different view on synthetic versus normal engine oils. We are no where near coming to a consensus on which oil is best. I think the bottomline is, as Pete126 states, it is a matter of personal choice. Having said that, we all seem to agree that one should avoid using cheap engine oils and change oil frequently to ensure engine longevity.