According to NBC 2016 guidelines, the standby diesel fire engine pump must be test run at least once a week for a minimum of 10 to 15 minutes. This ensures that the engine battery is charged, the diesel fuel lines do not have airlocks, the cooling system works, and the engine oil remains distributed. Leaving it idle for months will lead to battery failure and gumming of fuel, causing it to fail during a power grid outage.