Apart from the first 1000 km, I have used nothing but full synthetic oils in my bikes ever since I could get them.

Imo the rumours of sythetic-caused clutch slip are just that, rumours. My work TTR250 now has 65000km and about 4000hrs on the clock with no problems and the original clutch pack.

My 96 Tenere ran Mobil 1 4T or shell full synthetic for its 43000km. Again, no issues. etc, etc.

So mate, imo you can run whatever you like in your Tenere. It will tolerate any reasonable oil from mineral to full synthetic, heavy or light (as long as it's not too hot).

I use Penrite 5w-60, and have done for some years now.