Originally Posted by Fabrik8

You'll have to run much richer than that to have problems with washdown. You'll be fine, and the worst thing that will happen is the plugs might foul. If you carry a wire toothbrush with you you can just give the plugs a quick cleaning on the way home if you need to, but I seriously doubt plug fouling will be a problem.

Don't skimp on the oil change intervals though, because you might end up with a little more fuel than normal in the oil. I'm sure you're planning on changing the oil when you get it home anyway though, which is the first thing I do with a new car.

Unless you're using a wideband O2 sensor I wouldn't even bother trusting what the gauge says.