I recently got an email from a new cast iron owner asking, “Should I add oil to my skillet before or after heating it?”
I love when readers reach out with questions like this. One thing I’ve learned from turning these emails into blog posts is that when one person is wondering something, many others are too!
So let’s tackle this question about cast iron cooking.
When to Add Oil to a Cast Iron Pan
The short answer?
You can add cooking oil to your cast iron skillet either before or after preheating — it’s really your choice. Unlike with other cookware, the timing doesn’t make much difference with cast iron.
For non-stick pans, manufacturer instructions typically tell you to add oil before heating. That’s because empty non-stick pans can get dangerously hot on the stove, and their coatings shouldn’t exceed 550°F.
But cast iron is incredibly tough. The material won’t melt until it reaches about 2,200°F, so this precaution just doesn’t apply.
Whether you add oil before or after heating your skillet, what really matters is making sure it’s hot enough before you start cooking. Otherwise, your food will end up oily and pale instead of crispy and nicely browned.
Another tip for proper browning: don’t overcrowd the pan. Adding too much food at once drops the temperature dramatically, preventing a good sear.
How to Know When Your Oil Is Hot Enough
Forget about constantly using an instant-read thermometer — trust your senses instead.
When oil is ready for cooking, it will glisten and shimmer across the surface. It literally sparkles and seems to dance in the pan.
Butter works differently. After it melts, wait until bubbles form and then begin to subside before cooking. Butter contains about 15% water that needs to evaporate. When you see fewer bubbles forming, most of that water is gone, and your butter is probably hot enough.
Preheating Cast Iron
It’s perfectly fine to preheat your cast iron skillet. Here’s how I do it.
Cast iron conducts heat poorly — only about 1/3 as well as aluminum and 1/5 as well as copper. That’s why cast iron takes time to heat up. But once hot, it distributes heat evenly and holds onto it incredibly well.
Heat your skillet for 2-3 minutes before cooking. Food cooks best when it hits a surface hot enough to create an immediate sizzle. You can add oil before or after preheating — with cast iron, it honestly doesn’t make much difference.
Why Oil Sometimes Smokes
If your cooking oil starts smoking, you’ve probably got the heat too high.
Avoid heating oil to the point where it releases bluish smoke. When this happens, the oil develops a bitter taste and creates unhealthy free radicals.
Plus, the smoke leaves stubborn soot on your kitchen walls that’s hard to clean and might eventually require repainting.
All cooking oils have a smoke point — the temperature where they stop flowing normally and start breaking down. This process (called oxidation) creates an intense burning smell similar to food left too long on the stove.
Once oil starts smoking, there’s no fixing it — you’ll need to start over. Always choose cooking oil with a smoke point higher than the temperature needed for your recipe.
Best Oils for Cast Iron Cooking
Your oil choice matters more than you might think.
For high-heat cooking like searing steaks or salmon, use oils that can handle the heat: avocado, rice bran, safflower, or sunflower oil. These regular grocery store options remain stable even at high temperatures.
Save delicate oils and fats like extra virgin olive oil or butter for low to medium-heat cooking only. Surprised? You’re not alone. Few cookbook authors or TV chefs talk about oil selection in detail, despite how important it is for flavor and health.
Cooking Without Oil
If your cast iron is well-seasoned, you can actually cook with minimal or even no oil. The seasoning helps prevent food from sticking.
According to Dr. Stuart Farrimond, author of The Science of Cooking, oil does two main things: it carries flavor molecules while conducting heat to food, and it creates a lubricating layer between food and metal to prevent sticking. With cast iron, the seasoning largely handles that second job.
The “seasoning” on a cast iron skillet is a thin layer of carbonized oil that keeps the bare iron from reacting with oxygen and moisture. It protects against rust and creates a naturally non-stick surface.
Bottom Line
When cooking with cast iron, add oil before or after preheating — your choice. I usually add it before heating, as it helps me spot when the oil is hot enough without exceeding its smoke point.
A first-time cast iron skillet owner recently asked me, “Should I add oil to my skillet before or after heating it?”
I love when readers reach out with good questions like this one. What I’ve discovered through turning these questions into stories is that when one person asks, many others are wondering the same thing!
So, let’s tackle this reader’s question: Do you heat your cast iron skillet before adding oil?
When to Add Oil to a Cast Iron Pan
You can add cooking oil to your cast iron skillet either before or after preheating it; it’s really a matter of personal preference. Unlike with other types of cookware, this timing doesn’t significantly affect your cooking results with cast iron.
The owner’s manuals for non-stick frying pans typically instruct you to add oil before preheating. This recommendation exists because empty non-stick pans can quickly reach excessive temperatures on your stove, potentially damaging the polytetrafluoroethylene (PTFE) coating, which shouldn’t be heated above 550°F.
Cast iron skillets, however, are incredibly durable. Cast iron won’t melt until temperatures reach about 2,200°F, so the pre-oil recommendation doesn’t really apply here.
Whether you add oil before or after preheating your skillet, the most important factor is ensuring it’s hot enough before you start cooking. Otherwise, your food will turn out oily and pale instead of crispy and nicely browned.
Another tip to ensure proper browning: avoid overcrowding your skillet. Adding too much food at once dramatically lowers the temperature, preventing proper searing.
Many cooking experts will tell you to use an instant-read thermometer to determine when your oil is hot enough (often while recommending specific models with affiliate links). While thermometers are useful tools, it’s not practical to pull one out every time you cook.
How to Tell If the Oil in Your Skillet is Hot Enough
To determine when the oil in your pan is ready for cooking, trust your senses.
When oil starts to glisten and shimmer (sparkle and dance across the surface), it’s usually hot enough for cooking.
Butter works differently. After it melts in your pan, wait until bubbles form and eventually begin to subside before cooking. Butter contains approximately 15% water, which evaporates when heated. When you see fewer bubbles forming, most of the water has evaporated, indicating the butter is likely hot enough.
Can You Preheat Cast Iron?
Yes, it’s perfectly fine to preheat cast iron skillets. There’s no single correct approach, but here’s my method.
Cast iron has relatively poor thermal conductivity—only about one-third as efficient as aluminum and one-fifth as efficient as copper. This is why cast iron skillets take time to heat up. However, once hot, they distribute heat evenly and retain it exceptionally well.
Preheat your cast iron skillet for 2-3 minutes before cooking. Food cooks best when it makes sudden contact with a hot surface that creates an immediate sizzle. You can add oil either before or after preheating; with cast iron, the timing makes little difference to your results.
Why Is My Cooking Oil Smoking?
If your cooking oil starts smoking, you’ve likely overheated it.
Be careful not to heat oil to the point where it emits bluish smoke. When this happens, the oil develops a bitter taste and creates free radicals that can be harmful to your health.
Additionally, the smoke leaves sooty residue on your kitchen walls, which is difficult to clean and may eventually require repainting.
All cooking oils have a smoke point—the temperature at which they stop flowing normally and begin to break down chemically. This process, called oxidation, produces an intense burning smell similar to what happens when you leave something on the stove too long or use rancid oil.
Once oil starts smoking, there’s no salvaging it; you’ll need to clean the pan and start over. As a general rule, always choose cooking oil with a smoke point higher than the cooking temperature your recipe requires.
What Are the Best Oils for Cast Iron Cooking?
Your choice of oil can make or break your dish.
When searing steak or salmon fillets, use high-heat cooking oils such as avocado, rice bran, safflower, or sunflower oil. These readily available oils remain stable even at high temperatures.
More delicate oils and fats, like extra virgin olive oil or butter, should only be used for low- to medium-heat cooking. If this information surprises you, you’re not alone.
Few cookbook authors or TV chefs discuss oil selection in detail, which is puzzling given how crucial it is for both flavor and health.
Can You Cook Without Oil?
If your cast iron skillet is well-seasoned, you can cook with minimal or even no oil. The seasoning helps prevent food from sticking to the cooking surface.
In his book, The Science of Cooking, Dr. Stuart Farrimond writes that oil serves two purposes in cooking: it carries flavor molecules while efficiently conducting heat to the food’s surface, and it creates a lubricating layer between the food and metal to prevent sticking. In cast iron cooking, the seasoning largely handles the second function.
The “seasoning” on a cast iron skillet is a thin layer of polymerized oil that protects the bare iron from reacting with oxygen and moisture. This protection not only prevents corrosion and rust but also creates a naturally non-stick surface.
In Conclusion
When cooking with cast iron, you can add oil either before or after preheating your pan. I typically add it before, as it helps me identify when the oil reaches proper cooking temperature and ensures I’m not exceeding its smoke point.