Sunflower Oil is classed as an Omega 6 oil. Same for corn, soy, canola, and safflower. Although Omega 6 oils are generally good, most western diets are very high in Omega 6 compared with Omega 3. Sources of Omega 3 are flaxseed oil, walnut oil and fish.
To get the full benefits of these essential fatty acids (EFA's) your diet should have a balanced Omega 3 to Omega 6 ratio level.
If you are going to use sunflower oil then make sure that the linoleic acid content is high. Some producers will lower the content in the manufacturing process. Don't use any oils which have been hydrogenated.