Definitely change the oil! I help crew on a twin-engine nostalgia dragster - mechanical fuel injected SBC's running alky - and we change the oil in both engines every 4 runs. You won't believe how much alky gets in the oil and thins it out. Draining the fuel system completely is also a must as either ethanol or methanol causes more corrosion than gasoline. Too long to discuss here...check out the web for why.