If you started the car, but did not let it warm up completely (i.e., including the oil, which takes 10-15 minutes depending on use), then you actually caused the problem with your oil. Engines produce water as a byproduct of combustion, and a small amount makes its way into the oil. If you don't get the oil above 212F, the water never boils off and eventually you have the situation you describe.
You should change the oil immediately, and then drive it normally for a time and check the oil again. If you still see the "muddy" look, and particularly if it looks like chocolate mousse, you are likely leaking coolant into the oil, possibly from a blown head gasket. Take it straight to the mechanic in that case.
You should change the oil immediately, and then drive it normally for a time and check the oil again. If you still see the "muddy" look, and particularly if it looks like chocolate mousse, you are likely leaking coolant into the oil, possibly from a blown head gasket. Take it straight to the mechanic in that case.
