In general the synth blends will burn cleaner and with lower smoke.
However…
I’ve never see such a difference as when I switched my 150 Ocean Pro Johnson over from the cheapo oils like quicksilver or OMC oils to Pennzoil Premium Plus.
I was tired of the smoke and the fouling of these big engines, and a carbed 150 is such a gas pig that I was going through gallons of oil a season.
So I asked the boys who KNOW real world 2 stroke operations, I posted on a couple of saltwater fishing forums about 10 years ago. These guys are running big singles and a lot are running twins or triples and for many of them a “day” of fishing involves 100+ miles of running and 50+ gallons of fuel burned. They don’t buy gallons of oil, most of them at the time bought CASES of oil at a time.
The overwhelming response to question of best low-cost oil for performance and low smoke was Penzoil Preimum Plus. These guys were buying pallet loads of it from Walmart when it went on sale down in FL and the southeast.
What a difference.
Grouse