What oil is used in the bottom of a kawasaki 90 motorcycle?

This is a 1973 modelWhat oil is used in the bottom of a kawasaki 90 motorcycle?
Being it is a 2-stroke motor, that is the oil that your gears and clutch run in. You can use car oil like 10-40 or 20-50 or they make a specific gear oil for transmissions in 2-strokes. It holds up better to the stress. Being it's not a race bike I would opt for the cheaper car oil. Drain it at the bottom and fill through the cap. I don't know what model you have but most of the 90's had a dip stick in the cap.What oil is used in the bottom of a kawasaki 90 motorcycle?
I would use a decent name brand 10W40 oil in it...