Bad Fuel

[spareparts]

removing the old fuel is always the best idea, fuel starts loosing its octane after sitting less than 90 days. you might be able to get away with taking half out, but whats a replacement power head worth? It won't take much to detonate a piston with old gas. Inboards and I/O's can be more tolerant of old gas, but why risk it. I tell all my customers to keep the tank low(the whole condensation thing is BS)and add fresh fuel right before they take the boat out, that way, they always have the freshest fuel