My Cimatti Owner's Manual has this to say about lubrication:
"The engine is lubricated by mixing oil with the gas. Regular gasoline and a quality two cycle synthetic motor oil should be mixed according to the instructison on the can. If synthetic oil is not available, use two cycle motor oil on a 33:1 ratio."
So maybe the ratio for synthetics is lower in some circumstances. But the 33:1 has been beddy beddy good for my Minarelli for the past 25 years.