I was thinking about using Mobile one in my p1000-5. Has there been any discussion on this matter?
No. No one has discussed this.
Just kidding...
Religion. Politics. Oil.
More animosity has been started by discussions of these 3 than everything else put together.
If by mobil one you mean the motorcycle version, then yes, you can use it. ANYTHING that meets the specs laid out in the owners manual for viscosity and certification (IE JASO MAsomething) is fine. You DO NOT have to use Honda oil because there is nothing special about it, though it will certainly do the job quite well. There are many, many oils you can run just fine.
For the record, in my departed 700, i used:
Factory fill Honda
Honda HP4S
Mobil 1 motorcycle
Amsoil powersports 0-40
Rotella T6
The only real difference i could tell between any of them was during warm up, when the synthetics (all the ones i listed but the factory fill ) greatly shortened the time before the machine could be driven before slippage (the 700 is notorious for needing good warm up or the tranny slips in cold weather) and smoother shifts. Maybe a bit less engine noise as well. The T6 was much cheaper...and this tends to upset some people.