I don't want to get a "which oil" debate going again, just a snippet of info I was reminded of in a recent discussion, its backed up with the attached data.
The engine oil spec in the CT Manual states the oil type to conform to "JASO MA", Jaso is the standards board and "MA"refers to oil suitable for an engine with an internal friction type clutch, (MB is for engines like the OLD 1150GS which has an external car like clutch). Its nothing to do with the viscosity (ie-10w 30). Just something to remember when you are choosing top up or the next service oil and to distance the correct oil from car type specific oil. Just make sure it has JASO MA on the can
"JASO The Japanese Automotive Standards Organization (JASO) has created their own set of performance and quality standards for petrol engines of Japanese origin.
For four-stroke gasoline engines, the JASO T904 standard is used, and is particularly relevant to motorcycle engines. The JASO T904-MA and MA2 standards are designed to distinguish oils that are approved for wet clutch use, and the JASO T904-MB standard is not suitable for wet clutch use.
For two-stroke gasoline engines, the JASO M345 (FA, FB, FC) standard is used, and this refers particularly to low ash, lubricity, detergency, low smoke and exhaust blocking.
These standards, especially JASO-MA and JASO-FC, are designed to address oil-requirement issues not addressed by the API service categories.ils "