Best Oil for Seasoning Cast Iron: Ranked & Tested

Walk into any cast iron forum or Facebook group and ask which oil to use for seasoning — and prepare to duck. People have strong opinions. Flaxseed devotees will quote food science at you. Canola loyalists will call everything else overpriced. Someone's grandmother swore by bacon grease. Someone else says Crisco is the only answer.

So we cut through the noise and actually tested them. Here's exactly how each oil performs, what makes it work (or not), and our definitive ranking — so you can stop second-guessing your pantry and start building the seasoning your cast iron deserves.

What Makes an Oil Good for Seasoning?

Before the rankings, a quick lesson in the science — because once you understand this, you'll never have to Google "best oil for cast iron" again.

Seasoning isn't just coating your pan in grease. It's a chemical process called polymerization — when oil is heated past its smoke point, the fats break down and reform into a hard, plastic-like layer that bonds to the iron. That layer is your non-stick surface.

Two things determine how well an oil polymerizes:

1. Polyunsaturated fat content — oils rich in polyunsaturated fats polymerize more completely and form a harder, more durable seasoning layer. This is the most important factor.

2. Smoke point — your oven temperature must be above the oil's smoke point to trigger polymerization. Most people season at 450–500°F, so you want an oil that can reach that threshold without just burning away.

With that in mind — here's the ranking.

🥇 #1 — Grapeseed Oil

Smoke point: ~420°F | Polyunsaturated fat: Very high | Cost: $

Grapeseed oil is the near-unanimous winner among cast iron testers, food scientists, and serious enthusiasts — and it earned that reputation. It has one of the highest polyunsaturated fat ratios of any cooking oil, meaning it polymerizes into an exceptionally hard, durable seasoning layer. Multiple independent tests have found it creates the smoothest, most even coating after just two to three oven cycles.

It also happens to be cheap, neutral in flavor, and available at every grocery store. You can use it for daily cooking and seasoning — the same bottle does both jobs.

Best for: First-time seasoning, rebuilding seasoning, everyday maintenance, and high-heat cooking.

Pro tip: La Tourangelle is the brand most frequently recommended by cast iron enthusiasts for grapeseed oil — it's cold-pressed and higher quality than many store brands.

🥈 #2 — Canola Oil / Vegetable Oil

Smoke point: ~400°F | Polyunsaturated fat: High | Cost: $

This is what Lodge — the most trusted name in cast iron — uses to season every skillet that comes out of their foundry. That alone is a significant endorsement. Canola oil has a high enough smoke point, strong polyunsaturated fat content, a completely neutral flavor, and costs almost nothing.

In side-by-side tests, canola and vegetable oil perform nearly identically. If you have either sitting in your cabinet right now, it will do an excellent job. The seasoning it builds is smooth, even, and durable with regular cooking.

Best for: Budget-conscious cooks, beginners, and anyone who wants a no-fuss everyday option.

Note: These two oils are interchangeable for cast iron purposes — use whichever you have.

🥉 #3 — Avocado Oil

Smoke point: ~520°F | Polyunsaturated fat: Moderate-high | Cost: $$

Avocado oil's superpower is its extraordinary smoke point — the highest of any commonly used cooking oil. This makes it ideal for seasoning at very high oven temperatures (500°F+), and it creates a hard, resilient layer that holds up to intense heat in daily cooking.

The tradeoff is cost. Avocado oil is significantly more expensive than grapeseed or canola, and its polyunsaturated fat content is slightly lower than grapeseed (it's higher in monounsaturated fats). The seasoning it produces is excellent — just not dramatically better than grapeseed at a fraction of the price.

Best for: High-heat cooking, cooks who already keep avocado oil in the kitchen, and those seasoning at temperatures above 475°F.

#4 — Flaxseed Oil

Smoke point: ~225°F | Polyunsaturated fat: Extremely high | Cost: $$

Flaxseed oil became an internet darling for cast iron seasoning about a decade ago, largely because food scientist Sheryl Canter published a detailed post about its superior polymerization chemistry. She wasn't wrong — flaxseed oil is a "drying oil" that polymerizes aggressively and bonds exceptionally well to iron.

The problem is what happens over time. Many cast iron owners — and multiple independent testers — have found that flaxseed seasoning becomes brittle and flakes off after a few months of regular use, especially when cooking acidic foods or using the dishwasher. It builds a beautiful first layer but doesn't always hold.

It also has a very low smoke point (~225°F), which means you need to be careful with your oven temperature. And it's expensive, with a short shelf life.

Best for: Building a base layer on a freshly restored or brand-new pan — then switching to grapeseed or canola for maintenance.

Not ideal for: Long-term sole seasoning oil.

#5 — Crisco / Vegetable Shortening

Smoke point: ~360°F | Polyunsaturated fat: Moderate | Cost: $

Crisco has been used to season cast iron for generations and it works reasonably well. Its semi-solid state makes it easy to apply in a thin, even coat — which is actually one of the trickiest parts of seasoning. The smoke point is adequate for most oven temperatures, and it's widely available.

The downside is that vegetable shortening is lower in polyunsaturated fats than grapeseed or canola, so the seasoning layer it produces tends to be softer and less durable over time. It's a perfectly acceptable option, especially for those restoring antique pans with a traditional method — but not the best choice if you're starting from scratch.

Best for: Traditional cooks, pan restoration, and anyone who wants a time-tested method.

❌ Oils to Avoid for Seasoning

Extra virgin olive oil — The flavor and health benefits you love in EVOO come from compounds that burn off below 375°F, well before polymerization can happen properly. It leaves a sticky, gummy residue and imparts flavor. Save it for finishing dishes.

Butter — Too low a smoke point, too high in saturated fat. Great for cooking in your cast iron, terrible for building seasoning on it.

Coconut oil — Popular for its perceived health benefits, but it's high in saturated fat and low in polyunsaturated fat. It won't polymerize into a durable seasoning. Smells great while it burns, though.

Bacon grease / lard — A beloved traditional option, but food science has caught up with Grandma's method. Animal fats are high in saturated fat and low in polyunsaturated fat — the opposite of what you want for strong seasoning. They're wonderful for adding flavor when you cook, but they don't build the hard protective layer that keeps your pan non-stick.

The One Rule That Matters More Than Which Oil You Pick

Here's the thing most people get wrong: the amount of oil matters more than the brand.

Too much oil = gummy, sticky, uneven seasoning. Every time. No exceptions.

After applying your oil, wipe off as much as you can with a clean paper towel. Then wipe it again. The pan should look almost dry — barely a sheen. That whisper-thin coat is what polymerizes into hard, smooth seasoning. A thick coat just stays greasy.

The step-by-step method that works with any of the top-ranked oils above:

1. Preheat your oven to 450–500°F (or 225°F if using flaxseed)

2. Warm your clean, dry pan in the oven for 10 minutes

3. Remove the pan and apply a thin coat of oil with a paper towel

4. Wipe off the excess — then wipe again — until the pan looks almost bare

5. Place the pan upside-down on the top rack (put foil on the bottom rack to catch drips)

6. Bake for one hour

7. Turn off the oven and let the pan cool completely inside

8. Repeat 2–3 times for a strong starting base

The Verdict

If you want the short answer: buy grapeseed oil. It produces the hardest, most durable seasoning of any common cooking oil, it's affordable, neutral in flavor, and doubles as your everyday high-heat cooking oil. Canola is right behind it and equally excellent if you already have it on hand.

Everything else on the list is either situational (flaxseed for restoration), expensive (avocado), or outclassed by better options (bacon grease, EVOO). Keep it simple and you'll build a pan that lasts generations.

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