Let's start with the the claim that spray oil is a fat free way to cook. This is really a technicality based on legal definitions. Legally, something can be called fat free if it has less than 0.5 grams of fat per serving. So, you could technically make anything "fat free" by making the serving size really small. Sneaky, huh? So, one serving of spray oil (approximated by a 0.25 second spray) is "fat free" in the legal sense. However, oil is a fat and can never be fat free outside of the strange realities of the food retail market and US legal system. Not only that, but who actually only uses a 0.25s spray? I usually spray those bad boys for at least 2s, which automatically puts me up closer to 8 servings or more.
Next up is the issue of using spray oils with nonstick cookware. I know, I know, you're probably thinking why anyone would use oil on a "nonstick" pan. Well, truthfully, nonstick doesn't mean nothing sticks to it. It just means food is a lot less likely to stick than regular non-coated cookware. Anyhow, if you try using spray oil on your nice nonstick cookware, your nonstick cookware will start sucking really fast. Why is that? Most spray oils contain ingredients that bond to the nonstick surface when exposed to high heat and effectively make the surface no longer nonstick. Don't believe me? Here's the word from Calphalon:
I like to use spray oils for lowfat cooking. Can I use them in my Calphalon cookware?In case your Google-fu is weak, I'll leave you with a few more links discussing the nonstick cookware ruination caused by spray oil.
For cooking, the answer is NO, we advise against using spray oils in our cookware for several reasons. For baking with our Professional Nonstick Bakeware, the answer is YES, you can use spray oils with no trouble.
Cooking: Spray oil instructions usually direct you to apply the spray to a cold pan, then add your food. This is because spray oils contain a lot of water. If you spray it into a hot pan, the water boils away immediately and leaves you with a gummy residue. (Calphalon cookware calls for preheating the pan before adding any oils to make sure you get the cooking performance you want.)
Finally, let's cover the purely frugal rationale against spray oil. Let's face it, the stuff is just expensive. At my Trader Joe's, a 5 oz can costs $3. Some basic math tells me that comes out to $9.60 when scaled up to 16oz. $4 gets me an economical but still decent 16oz bottle of olive oil. Paying nearly $10 should get me a really nice olive oil. I think I rather prefer spending the extra money on a nice olive oil rather than a pressurized can of cheap olive oil.
If you really must have a spray oil, just forego the expensive aerosol cans in the grocery store. You can go the DIY route with a plastic spray bottle or a Misto (pictured to the right). They're refillable, don't require chemical propellants, and you can pick whatever oil you want. Now go forth and use your newfound knowledge for the powers of good [cooking].