Opal fuel features a minimum octane rating of 91, making it a direct functional equivalent to standard regular unleaded petrol found across Australian service stations. It conforms completely to the stringent benchmarks outlined in the National Fuel Quality Standards Act. Because of this 91 octane rating, it is entirely safe and compatible for use in any standard car, four-wheel drive, boat motor, or small engine where the manufacturer specifies regular unleaded fuel as the minimum requirement. However, it is not suitable for high-performance engines that explicitly demand premium unleaded petrol with an octane rating of 95 or higher.