Synthetic oil worth it? 18k hour yamaha generator says no.

I generally use whatever the Mfg calls for with oil. I use mostly synthetics or syn/blends in everything.

The reviewer with the Yamaha's is a testament to the durability of the machine rather than a careful review with good maintenance. His excess carbon problems may be because of the Pennzoil or may be because of the hard use. Rode hard and put away wet is my take.