This is one of those questions that almost always degrades into a “my oil is better than your oil” discussion on most forums. My suggestion is to use whatever the manufacturer recommends in the manual. Why ? Because while the motorcycle is under warranty, the manufacturer is likely to refute any warranty claims where the motorcycle was not properly maintained. This includes oil changes with the recommended oil.
The manual will usually have an oil change interval they recommend and a viscosity and type as well as service classification and oil type they recommend. The service interval is not to be exceeded. You can change it more often than recommended, if you like, especially if using it in a commercial capacity.
Viscosity of the oil is represented by a number like SAE 30 or 10W40. This describes how thick the oil is. Single viscosity oils have a single number, e.g. SAE 30 while multi-viscosity oils have two numbers, like 20W50. They indicate the viscosity when cold and when warm. Generally, thicker oil is called out for warmer climates and thinner oil for colder climates. In a pinch, it is OK to use a different viscosity as long as it’s close to the recommended viscosity, but this is not recommended for normal use. It’s also not recommended to mix oils with different viscosity, unless you have to.
The manual will call out a service classification. Service classifications are indicated with a two letter code, like SF or SG. These codes indicate how much detergents and additives they have added, mostly to meet emissions regulations. The higher the second letter, the newer the code is. It is normally OK to use a classification that is newer (higher letter), if the applicable classification cannot be found. However, it is best to check with the manufacturer/dealer to make sure. Classification codes that start with the letter S are for gasoline engines, normally found in motorcycles. Diesel engines use different classification codes that start with the letter C, e.g. CI-4. It is OK to use diesel engine motor oil if it also has the appropriate S classification.
Many motorcycles have wet clutches. Wet clutches are bathed in the same oil as the engine oil. You should not use engine oils that have special “low friction” modifiers, as they can interfere with the clutch function. This is usually called out in the manual as well.
Finally, sometimes the manufacturer will recommend a specific oil type. Basic motor oil is distilled from mineral oil. Synthetic motor oils are motor oils that are synthesized to have better consistency and better specifications, but are more expensive. There are also blended oils which have a mix of both as a compromise. In general, it is OK to use synthetic oils in place of mineral oils, but not the other way around when the manufacturer recommends synthetic oil.
While under warranty, document when you change your oil, with notations on the type of oil and oil filter used. It’s often best to have it changed at the dealership and save the receipt. It is always a good idea to keep documentation of oil changes and other maintenance events in any case.
While it is peace of mind to use more expensive name brand oils, it matters very little, as long as the oil you use meets the manufacturer’s recommendation.
It is rare to damage your engine if you use the recommended oil. Most engine failures are the results of misuse, or infrequent maintenance. For example, running the engine with low oil or coolant levels, or dirty air filters or too hot for periods of time.