Glad to hear that Keith, running straight petrol would ruin it very quickly, and it happens surprisingly often when someone gets his/her first 2 stroke. The PowerTorque Engine Manual says 25:1, and I suggest you stay with that - the oil manufacturer's ambitions may be valid but since he hasn't done the testing and development that Victa has, it seems best to disregard them.
If the mower is starting really easily, it sounds as if the spark plug is in good condition. They don't last all that long on 2 strokes, and cleaning them isn't completely effective, but if you just wait for the mower to get a bit harder to start and just a little sluggish compared with the way it is now, you can take action at the right time. Incidentally sick spark plugs don't normally damage anything, they just annoy you, waste a lot of fuel, and cause you to wear out the pull starter.
I'll wait until tomorrow then if no one has posted anything more, I'll close this thread.
