I have a duel fuel NF Fairlane, 220,000 k and the engine shows no sign of wear at all.
Gas has a couple of advantages over petrol.
1. It has an octane rating of around 110 which is good, no more pinging.
2. It enters the cylinders as a gas, and not as a vapourised liquid as does petrol. Think of the oil film on the cylinder walls, a gas will not dilute or wash off this oil film, petrol will. Hence longer engine life.
3. Becasue it is a cleaner fuel, the engine and exhaust systems will not clog up with carbon.
4. Its cheaper - who cares about performance, you are only racing towards the next red light!
"I married Miss Right. I just didn't know her first name was Always."