The answer is that there is an answer to every question, and unfortunately this means that there is no one simple answer. There are many different factors that determine the health of your scalp and whether or not you are going to have oily hair, and there are some treatments out there that do work, and some that don't.
Dandruff is typically caused by clogged pores. When you have an oily scalp and you have an over production of sebum oil, you get clogged pores, which are usually the cause of the flakes you're seeing on your pillow case, in your carpeting, and on your clothes. The most common treatment for dry hair that is oily is conditioner, but even then there is no one treatment that works for everyone.
There are different ways you can combat dandruff, and all of them are completely natural. The easiest method is through prevention, because it's easy to say "I'll try to keep my hair clean", but how often have you tried to wash your hair and noticed it still looks greasy? You don't have to quit shampooing, and don't cut back on the amount of times you shampoo, because if you can wash more often your chances of having a bad scalp and itchy scalp are going to go down.
Excess oil is put onto your scalp from eating things that are greasy and from coming into contact with too much heat. Oil gets trapped on your scalp and can't be washed away, so it clogs up your pores and causes flakes to form. All you need to do is remove the excess oil and get rid of the excess oils on your scalp, and then you can relax.
There are many different ways you can avoid having an oily scalp, but none of them are going to make your head feel better. It's not a lack of something that is causing the problem, it's simply that your body is attempting to deal with an imbalance. Getting rid of excess oil will help to reduce this. Also, read best permanent hair dye in this post.
You can also use natural cleansers, such as tea tree oil, lavender oil, and lemon oil. All of these are organic, and they contain essential oils which are naturally antiseptic and antibacterial. So you'll be able to reduce dandruff by killing off any germs that have accumulated on your scalp.
Shampoo is another way to combat the effects of a greasy scalp. Once again, you can try all the commercial shampoos, but they don't work for everyone. Some people have oily scalps, and some don't. So, if you get into the habit of using the wrong kind of shampoo you may end up with a buildup of toxins in your scalp, which won't cause you any problems.
I'm sorry that you're having trouble with oily scalp. Your condition doesn't have to be this way, and there are plenty of treatments out there that work great. Take the steps you need to take to get rid of your dandruff and start living the life you've always wanted to live.