Lets talk about oils. Yes, I know there are some who regard "oil" as a bad word. I'm not kidding, I know people like that. Anyway, when used in moderation, its actually good for you and of course, helps your food taste better.
Lets go through the list of more common oils we find in our stores here and their uses:
Extra Virgin Olive Oil - Great fruity flavor, best used in salad dressings, dips and sauces. Or for drizzling as a finishing touch to a dish. Not recommended for frying and over the stove cooking, mainly for 2 reasons, it has a low smoking point and strong flavor. The fruity flavor can alter the flavor profile of your dish.
Extra Light Olive Oil - Extra Light does not mean healthier. It just means extra light flavor. As opposed to Extra Virgin Olive Oil. Use as you would regular vegetable oil. For pan frying and roasting.
Vegetable Oil - May come from various sources, soya-bean, palm, corn, sunflower, canola etc.. General use oil for over the stove cooking. For frying, sauteing roasting etc. For a healthier choice, I prefer using Canola oil.
Grapeseed Oil - A great neutral flavoured oil, use as you would vegetable oil, but it is rather costly, I do not use it generally and Canola Oil does what I need it to do.
Peanut Oil - A great oil for high heat frying and deep frying. Reason being, peanut oil has a high smoking point. Meaning, it takes a higher temperature to "burn" or "smoke" peanut oil as opposed to other oils.
Flavoured nut oils, like macadamia, walnut etc.. - These are best used for drizzling over dishes, salads and some desserts.
Sesame Oil - Rich fragrant oil from toasted sesame seeds. Used for drizzling over Asian dishes (Chinese mostly) and sometimes in marinades as well.
You generally do not need to spend a lot just to have every type of oil in your kitchen. Know the oils and what you need them to do and just stock up on whatever you need. I personally have Extra Virgin for salads, Vegetable Oil/Extra Light Olive Oil for over the stove cooking and sesame oil in my pantry.