It's not the oil. 15/50 synthetic is fine. Top off the oil/add oil until you are at the full level on stick without screwing it in wile it's on the center stand, on level ground.
I just figured out that the topcase makes my scoot sit on it's rear wheel, when I moved it over to
the front wheel, the level went down even more.
I think your a little low on oil, and when you take off fast the oil sloshes to the back side on the engine and the sensor light comes on. I would be surprised if this did not cure it? When my sensor light came on on my X5 , I stoped and checked the level and all was fine, so I knew it was the sensor. And my light stayed on all the time. So I think your a little low on oil, and it's not the sensor.
Yeah, you're probably right, I added a bit more, checked again, will take a few rides and see if it happens again.
I'm probably around 1,15 to 1,2L now.