Cooking oil and gasoline (a hydrocarbon) are not amphipathic molecules because they do not have a polar or charged region. Amphipathic hydrocarbons or molecules are those with both hydrophillic (water loving ends) ends and hydrophobic ends (water hating ends). Examples of such molecules are phospholipids and detergents such as soaps and soapless detergents. Cooking oil and gasoline on the other hand are purely hdrophobic or non-polar (water hating), meaning they can not react with water.