What type of engine oil should be used on a Yamaha XV 535 Virago?

Viscosity

Consistently below 15 degrees C (60 degrees F) SAE 10W30

Consistently above 5 degrees C (40 degrees F) SAE 20W40

The above is correct BUT DO USE GOOD motorcycle oil. I unfortunately got some from a superstore and it screwed up my starter clutch. I changed the oil and filter, and now it is getting better and even starts no problem after first start. If it does not start I have to engage second, and pull bike back to engage the sprague clutch and then whilst going back pull in clutch and the engage neutral and she will normally start.

The same is true for any car oil, do not use it not even for topping up!