Switched to SHELL primo (from BP) a couple weeks ago and getting 2mpg's better mileage.
Maybe the scoot is just getting broken in, or benefiting from warmer temps, or the newly retired Stig is more aerodynamic !!
I have been running it at higher speeds since no longer simply commuting in town.
Riding more at 55mph and 7200rpm's, indicated.
Faster too?
A little over 79 MPG with NGK Iridium plug and 14g Dr Pulley sliders.
RPM's would likely be closer to 8000 or above, at speed with stock rollers.
(Dr P's lowered the Burgman's rpm's by @1100 at highway speeds)
Stig