Ok. Someone know how many liters g290 zenoah can drive? And is it better than CY?
Here is the story on oil any good premium brand oil based, castor synthetic blended oil or full synthetic oil is good. A few things to consider does the gasoline you are running contain ethanol? If so stay away from synthetics and castor blended oils.
Do not buy oils formulated for lawn and garden equipment get good quality oil used in the ATV or Motorcycle business.
Some brands if you can find them that are proven.
Maxima Castor 927
Polaris Ves Gold
Always run at 25:1 running less oil does not create more power that is a missconception that alot of people have. The entire purpose of the oil and ratio in our small engines is for Cooling, Lubrication and creating Compression.
Zenoah states that inspection of their motors should occur every 25 hours, Replace jug and piston if showing wear. Zenoah has much better plating than CY.