Independent testing on outboard engines was conducted at Orbital’s Perth laboratory to determine whether running Opal fuel had any detrimental effect on engines. Opal fuel was used to run a boat engine for five hours a day over three consecutive days. There was no significant change seen in the condition of the inlet ports, valves, fuel injectors or spark plugs nor a significant reduction in flow rate which would indicate fouling. Testing on the field was also undertaken to ensure that the results for Opal fuel were equally demonstrable outside the laboratory. The testing evaluated the engine’s performance and smoke output when in idle, mid-power and with the throttle wide open on an Evinrude 115HP E-TEC outboard engine. The engine did not experience hard-starting or rough running when using Opal and engine stability at an operation mode of 2200-2500rpm even appeared to improve.