The Oil and water will not mix together for long, and will separate, with the oil floating on the water. It is possible to get the oil to mix and stay that way when you create an emulsion. An emulsion is a mix of unblendable liquids, and an emulsifier is the substance with helps achieve this. You may be familiar with this in cooking (egg yolks, mustard in salad dressing, etc)
Oil and water are very different from a chemical structure view: oil is non-polar (the electrons are evenly spread around), and water is polar (the oxygen part of water tends to pull a Little more on the electrons than the hydrogen). When the two compounds mix, they will eventually separate leaving the lighter, non-polar oil on top with the more polar water at the bottom. If a compound called an emulsifier is added, the oil and water stay mixed (creamy salad dressing, lotion, mayonnaise). An emulsifier allows the polar and non-polar compounds to interact (mix) better. Lemon juice and beeswax are natural emulsifiers.
According to Google and my mom when you mix oil with water the two substances won't dissolve they still keep their own matter so it's a mixture(a mixture is when you mix two or more substances together but they still keep their own identities)