Let me guess - IP = industrial petrol? intraveinous peroxide? instantaneous phazor?
Seriously though, I seem to remember when I were a lad the old Nimbus (Westland Scout/Wasp) could be adjusted to run on just about anything carbon-based that was liquid enough to get through the fuel nozzle, from kerosene, diesel to forecourt petrol (although I think TBO dropped to about ten hrs on petrol).
Today methinks regardless of whether or not you've got pax or any other consideration you either run whatever has been blessed by he who manufactured the beast or you deserve the big bang when it all turns to rats. You can't be worried too much about cost if it's for a twin....unless you pinched it..... (Assuming of course that you're not evacuating from a war zone, but then if that's the case it's unlikely you'll have time to read this....)
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Ground tested, no fault found