So Im not a OB mech, im a motorbike guy. but my explanation.
The design of two strokes mean the cranks are lubricated by the oil that is either pumped into the crank directly or mixed with the fuel (which is pumped around the crank) to lubricate it. Two strokes are basically a "dry sump" hence why there is no oil to change like your std car.
As the crank in most OBs are lubricated by oil being mixed into the fuel, then being mixed around the crank - this means the TYPE of fuel plays a part in the process.
WHY
A Two stroke crank has rubber seals that segregate each cylinder "web" off and ensure additional air does not get sucked in. Extra air being sucked in = leaner mixtures which will hole a piston and blow a motor.
The Ethanol blended fuels has been known to be "not as good" for rubber parts. On your car there are very few rubber parts that the fuel is directly in contact with. In your Tohatsu, there is. And they are pivotal to your engines reliability.
Accordingly my old 1973 3 cylinder Two stroke Kawasaki motorcycle (very similar to an OB motor) should not run on ethanol blended fuel - even thou the 98 (octane rating) is desired, that blend is not.
Octane rating (the number 91,95,98) is loosely about how stable the fuel is when it gets or is about to be ignited - which is more pivotal when you have a higher compression motor or a boosted/turbo motor. I.e your subaru WRX with a big turbo wants 95 octane Min.
I have attached a picture of a motorcycle two stroke crank - you can see the black rubber seals sitting in-between the main bearings. Note the only way to change these if they become damaged is to strip the motor all the way down to the crank as pictured, and then pull each part of the crank apart...........consider this open heart surgery and replacing the seals/valves inside the insides of your heart.