Just started using synthetic oil. Not sure there is any difference except the price has come down significaNTLY. A mechanic friend says that with older vehicles, synthetic cleans up the metal and makes for longer engine life. If using light oil in older cars particularly, leaks can develop i have noticed.
Some misnomers:
If "The price has come down" you are probably buying a Hydro-Cracked oil like Castrol SynTec, Rotella and Mobil 1 Automotive.
ALL Synthetics are not alike.
A True Synthetic made from a PAO or Ester Base Stock and will be higher priced..
Synthetic Motorcycle Specific will be around $8.00 and up per qt. Have seen it for $17.00 (US)
On that note, all synthetics Do Not clean. Usually PAO w/Esters and Ester based oils will clean.
Synthetic oil is Not "Lighter" than petroleum. That is what the viscosity grades are for.
Synthetics do not cause leaks. The leak was already there and the Synthetic cleaned the junk out caused by paraffin deposits. In many cases, such as seal leaks, synthetics will clean the deposits out, soften the seals and slow or cure the leak.
I have switched vehicles with in excess of 200,000 miles to synthetic with no issues.
The Best isn't cheap
Cheap isn't The Best