To Preheat or Not: When to Add Oil to the Pan

So, I want you to pick a side. On the one side, you’ve got people who add oil to the pan when the pan is still cold, as soon as the pan is added to the stove top. On the other side, you’ve got people who wait until the pan is ripping hot before they add oil, so that the oil runs like water.

Which of these two sides do you fall into? This isn’t some kind of stupid trick question. This is literally like the blue and black or white and gold dress fiasco. There are professional, well-respected chefs in both camps.

But in my opinion, there is a scientifically correct answer. Let’s find out what that is.

One of the many nuggets of wisdom in Samin Nosrat’s book ‘Salt, Fat, Acid, Heat‘ always stood out to me: always preheat your pan before adding your cooking fat, Whether that’s olive oil, rendered animal fat, or butter.

Since reading that, I followed the advice religiously. But when I started researching this question, I realised that Samin’s advice isn’t as common sense as it she would have you believe. In fact, it’s contentious at best.

But first, what do we actually mean by preheating?

What is pre-heating?

Preheating is the process of heating a cooking vessel to the temperature that you want to cook at and then adding your cooking fat.

The alternative to this is to add oil immediately to a cool pan and then bring both the oil and the pan to the temperature that you want to cook at.

So why bother preheating? Why not just add the oil straight away?

Well, Adrian Cheatham argues that preheating your skillet is one of the fundamental things of cooking. Meanwhile, Samin argues that when preheating, the fat spends less time heating up, meaning less time to deteriorate. As oil is heated, she says, it breaks down, leading to flavour degradation and the release of toxic chemicals. Food is also more likely to stick to a cold pan. Another reason to preheat, supposedly.

Okay, so Samin presents two reasons here: fat degradation and preventing food from sticking. Let’s explore both.

First, fat degradation. Samin is arguing that by adding fat later, it has less time to deteriorate. The legendary Harold McGee agrees, adding that degraded or burnt oil can lead to low nutrition, plus it may lead to food sticking and turn the oil viscous and gummy.

However, a crucial aspect neither discusses is that fat primarily degrades when heated above its smoke point, the temperature at which it begins to smoke and decompose. In most cases, you’re not doing that.

Here are a few instances of various fats and their respective smoke points from McGee’s cookbook ‘On Food and Cooking’:

Most neutral oils have a smoke point above 200 degrees Celsius (that’s about 400 Fahrenheit), which is well above the temperature required for more cooking tasks like sautéing, which is best performed at about 160 degrees Celsius (that’s about 320 Fahrenheit).

This is where the conflict starts, though. Another legendary cooking author, J. Kenji Alt-Lopez, argues that if you’re adding fat to a pan that is hotter than the fat’s smoke point, it doesn’t matter when you add it. If the pan is hot enough, he reasons, the fat will degrade regardless of when it’s added.

But I’m not convinced. While fat above its smoke point will inevitably degrade, this report claims that the longer the fat is heated above its smoke point, the more it degrades and the lower the smoke point becomes in turn. So for the first time ever, and I mean the first time ever, I have to disagree with Kenji.

The logic around fat degradation only applies when you’re cooking above the fat’s smoke point. In such cases, it’s best to add the fat as late as possible to reduce the amount of time it has to degrade. But if you’re not heating the pan above the fat’s smoke point, it doesn’t really matter when you add the fat. At least in terms of degradation.

What about the whole thing about preheating the pan to prevent sticking?

The common myth is this: cold oil, hot (i.e., a preheated) pan, and food won’t stick.

This “works” because the oil is technically never cold. When you add cold oil to a hot pan, the oil is immediately heated. Therefore, technically, it’s hot pan, hot oil, food won’t stick. You can achieve this regardless of whether the oil is added immediately or gradually brought to temperature. In other words, it doesn’t matter whether you preheat or not.

I mean, let’s look at Samin’s statement again: “Food is also more likely to stick to a cold pan. Another reason to preheat.” The food is likely to stick to a cold pan. This has nothing to do with whether the pan is preheated or not.

To avoid sticking, it’s simply a case of ensuring the pan is hot enough when you add the food.

So again, if the pan isn’t heated above the fat’s smoke point, there’s no benefit whatsoever to preheating, at least from a food-sticking point of view.

I mean, I tried this out with some salmon. I cooked one salmon with oil that had been added to a preheated pan and one when the oil had been added right away. The difference? Absolutely non-existent. What would have made it stick? Adding it to a cold pan and then not adding enough oil.

So a hot pan is always necessary, then, right? Well, not quite. If you want firm vegetables or a nice browning on your protein, then yes, preheat the pan and make sure it’s at the right temperature before you add the fat. But stealing another line from Mr. Lopez here, if you’re just looking to sweat some vegetables – that is, use gentle heat to soften them and draw the flavours out – then there’s no benefit to preheating the pan.

In this situation, you can add the oil and the ingredients to a cool pan and bring it to heat. There’s no benefit to preheating at all, neither for the fat nor for the ingredients.

When it comes to preventing food from sticking, the temperature of the pan, not whether or not it’s preheated, is the only detail that matters. And even that factor isn’t always important.

When should you preheat the pan? There are still some situations where preheating is necessary.

Here’s the big one that we’ve already alluded to: cooking above the fat’s smoke point. For example, searing meat with butter or cooking in a wok at a ridiculously high temperature to achieve “wok hei”, that slightly smoky, charred metallic flavour that only comes from a seasoned cast iron or carbon steel pan heated to ripping hot temperatures.

In either of these situations, adding fat at the start and bringing it to temperature is a recipe for disaster. The fat will be a smoking mess before you even think of adding your ingredients. Instead, the pan should be brought to temperature, and then the fat and ingredients should be added in quick succession to minimise the time the fat has to burn.

Other than that, well, I can’t see any reason to preheat the pan before adding fat. As discussed, the main factor is the temperature of the pan. Is the pan hot enough? But what about some other arguments supporting preheating?

One common argument is that preheating leads to even cooking. Some argue that preheating a pan with oil forces the oil to pool at the sides, leading to an uneven coating on the pan. By the time the pan comes to temperature, they reason, the edges will be cooler than the centre.

Well, yeah, that’s kind of true, but let me explain. I tested this by preheating a pan without oil and then adding it and checking the temperature at different points in the pan. And by adding the oil straight away and doing the same thing. When the pan with the oil that had been added immediately came to temperature, the pan did have different temperatures at different points. In some cases, as much as 20 degrees Celsius difference.

But there are two things to point out here: first, this discrepancy existed when the oil was added to the preheated pan too. Second, the centre of the pan was actually hotter than the sides in both cases. So that’s the exact opposite of what this argument is saying. Okay, so it’s not comprehensive science, but I’m pretty confident in saying that this theory is out the window.

Another argument is that preheating “closes the pores” of the pan. On a microscopic level, a pan is a rough surface of lots of little pores. When fat is added and brought to heat, it creates a smooth surface, and those pores essentially close up.

One argument is that if you add food to a pan that isn’t hot enough, the pores, as they heat up, will seal up and grip the food. Therefore, you never want to add food to cold fat. But again, this has nothing to do with preheating. Whether or not it’s preheated doesn’t matter. What really matters (and I’m saying it again) is that the pan is hot enough.

Cooking above smoke point? Preheat. Below the smoke point? No preheat. Right? It depends.

There’s more to consider than just the relationship of the fat and the heat of the pan.

It could, for instance, depend on which kind of pan you’re using. For example, preheating a non-stick pan can be pretty dangerous. These pans heat quickly, and high dry heat can cause pans to deteriorate. Cook’s Illustrated advises not preheating an empty non-stick pan because dry, empty pans heat up faster, and non-stick coatings break down when heated above 260 degrees Celsius (that’s 500 Fahrenheit). In other words, you’re likely to burn a pan if it’s empty. Non-stick pans aren’t ideal for any sort of high-heat cooking anyway. If you want to sear some meat, for instance, you’d be better off in a cast iron or a stainless steel pan.

As for wok searing, J.B. Prince Vice President Tim Mussig wouldn’t ever recommend a non-stick wok.

“This wok that we have in front of us has a non-stick coating inside, something I would never recommend. While cooking is meant to be done at a really high heat, non-stick coatings are really not friendly to high heat. The marriage here just doesn’t make sense.”

Only stainless steel, cast iron, or carbon steel pans truly necessitate preheating.

Yet, even that may be iffy. Some manufacturers suggest not preheating their stainless steel pans, for instance. But it’s not just stainless steel. Lopez-Alt argues that preheating a cast iron pan can lead to cracking, though he does caveat that such instances are rare. The same applies to enamel cast iron pots as well. Adding fat to a preheated enamelled pot can cause a thermal shock, which will in turn crack the pot.

In my opinion, you need to weigh the pros and cons for preheating. If you want to sear a steak in butter, there’s just no way you can do it if you add the butter to the pan immediately. It’ll be a smoking mess by the time you start searing. Preheating is simply a risk you’ve got to take. It might also depend on what you’re actually doing. I’ve already given examples of when you’d want to preheat, that is, cooking at any temperature above the fat’s smoke point.

And while most of the time there’s no harm in preheating pans when cooking below the smoke point, there is one exception: deep-frying or pan-frying. Imagine pouring the amount of oil you’d need for pan-frying or deep-frying into a hot pan. That’s a guaranteed holiday to the local burn ward. Without exception, oil for deep-frying or pan-frying should be added immediately.

When to add oil to the pan?

So what’s my conclusion then? What is the correct answer? Well, to be honest, it’s mostly preference. Obviously, there are exceptions.

If you’re searing or wok-frying, you want to add the fat as late as possible for all the reasons that we’ve already discussed.

If you’re deep-frying or pan-frying, you want to add the oil immediately for all the reasons that we’ve already discussed.

And if you’re using a non-stick pan, you likely want to avoid preheating altogether.

Beyond those exceptions, it’s all preference, really. As long as you’re not heating the fat above its smoke point, and the pan is hot when you add the food, there’s no objective advantage or disadvantage to adding the fat to a hot pan or a cold pan. And even then, ensuring the pan is hot isn’t always necessary.

For example, if you’re sweating onions, one argument that some people like to use for adding the oil immediately is that you can use the oil as a sort of temperature gauge. You basically wait until the oil becomes runny or begins to shimmer, and that way you know that the pan is ready for food to be added. But there is an alternative and safer temperature test using water and the Leidenfrost effect.

It works like this: you preheat an empty pan on whatever temperature you want to cook at, and you keep adding water until you get this effect.

Once the water acts like this, you know that the pan is ready for cooking. But while this is potentially safer than having a hot pan of oil burning away if you leave the pan unattended, it could get way too hot way too fast. Because, as I’ve already mentioned, pans that are empty heat a lot faster.

Here’s another thing that you need to consider: which context are you cooking in? Are you cooking in a professional kitchen with multiple responsibilities, or are you cooking alone at home with only one pan to worry about?

If you’re cooking in a professional kitchen and you’ve got a big hot pan of oil kicking around, that’s gonna be a lot harder to deal with than a pan that’s just, say, too hot. A pan that’s just too hot? Well, just take it off the stove and let it cool down. A steaming hot pan of oil? Well, that invites a lot more dangerous situations, doesn’t it? And what are you gonna do with all that burnt oil, anyway?

But at the end of the day, only you can choose what makes sense in your situation.

Decide how much risk either approach has, how much of a difference, if any, it’s going to make on the actual food, and whether or not the equipment that you have is appropriate. I promise that I won’t judge you whichever decision you make. Well, I might.