Suzuki recommends SAE 10W30 motor oil for the TS90. This is a good all-around oil that will provide adequate protection for the engine in most climates.
If you live in a very cold climate, you may want to consider using a slightly heavier oil, such as SAE 10W40. This will help to protect the engine from damage caused by cold weather.
Conversely, if you live in a very hot climate, you may want to consider using a slightly lighter oil, such as SAE 10W20. This will help to prevent the oil from breaking down in the heat.
No matter what climate you live in, it is important to change the oil in your TS90 regularly.
