The 5 Best Penetrating Oils For Seized Bolts, Based On Reviews

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When seized bolts get in the way of finishing a repair job, the right penetrating oil can be the difference between wrapping up a task in minutes or wasting hours wrestling with rust. But when you're faced with rusted threads or a broken bolt in an engine, those frozen threads can derail an entire project. Heat, force, and other spur-of-the-moment improvisations can make things even worse: snapping bolts, stripping heads, or even damaging the surrounding parts. You need to be able to reach for the right product to get that seized bolt out the fastest. That's why mechanics and DIYers alike rely on penetrating oils designed specifically to break down rust, seep into microscopic gaps, and re-lubricate metal surfaces from the inside out.

But how can you know which penetrating oil to grab? After all, not all penetrating oils cut through corrosion the same. (Reviews across the internet make that clear.) Some formulas act quickly but don't cling. Others lubricate well but take too long to work. To help narrow it down, we dug through all sorts of Reddit threads, hardware store reviews, and forums to find which brands consistently perform best under real-world conditions. Based on our research, these are the five that stand out the most.

First up: Liquid Wrench Penetrating Oil. As its name suggests, this stuff has earned quite a loyal following for its performance on rusted bolts. The formula is made to seep in deep, lubricate the seized bolt, and cling to the metal surface for less friction and easier removal. Reviewers on Reddit praise it for being as fast-acting as it claims to be. ("Liquid [W]rench is good stuff," as one put it.) 

Walmart's user review section also has nice things to say. Shoppers have it at a 4.6 out of 102 ratings, with one user even praising it for the way it "loosened a stubborn, rusted bolt within minutes and required minimal effort." Reviews are just as nice over on Amazon, where it sits at a 4.7 out of 2,173 ratings. There, users working on old, rusted cars say Liquid Wrench helped "Every single one of the bolts [come] out easily and none of them broke. I've never had such a painless experience working on any car."

Another option is PB B'laster. This brand been around since 1957, which is a testament to its quality in and of itself. User feedback is further proof: "Just like its name it blasts into any hard to reach area. Loosened rusted bolts and door hinges making the job easy," said one Home Depot reviewer. There, it's sitting at a 4.4 average rating out of 1,541 ratings. Amazon has it at a slightly higher 4.7 out of 1,547 reviews, with one reviewer calling it "the best stuff out there" in their opinion.

PB B'laster dubs itself the number one-selling penetrant, and it's not difficult to see why when you read what people say about it. One Reddit user said it's "good stuff, and if you're planning ahead to do something on the weekend, just spray everything down a day or two beforehand for best results." As an added appeal: The product also underwent a recent redesign, so it now includes the "B'laster ProStraw" (basically a version of that iconic red straw on a WD-40 can). More on how WD-40 compares to PB B'laster in a second.

If those two don't work for you, try Kroil Penetrating Oil. (You might also know it as Aerokroil.) As Amazon reviews will tell you, it's like a miracle worker when it comes to freeing up seized bolts. In fact, they say it works so well, you only need to use a little bit to get the job done. It's earned a 4.8 out of 3,415 similarly glowing ratings on Amazon's site. Home Depot has it at a perfect 5-star rating from 1,071 users, with people over there heaping tons of praise on it for "[turning] what could have been a nightmare into a straightforward repair, as one put it.

Its manufacturer, Kano Laboratories, says that the oil's engineered to penetrate faster and deeper than its competitors and can handle seized bolts, motorcycle chain components, rusted hinges and stuck rollers. Yet, despite its popularity and solid reviews, Reddit users make note of the fact that it's pretty hard to find in stores. One user said, "Kroil is the best canned stuff, if you can find it, but [PB B'laster] is more common." Another agreed: "Kroil if you can find it, PB when you inevitably can't."

Of course, we can't forget to mention the classic, WD-40. It's one of those products people have on-hand no matter what. Maybe it's because they say you can use it in all sorts of unexpected ways? Even if you look past that marketing fluff, though, there's no denying the number of positive reviews online for removing seized bolts. Home Depot's website has it at a 4.7 out of 3,647 ratings, with users saying they've "been using WD40 for many years," calling it a "great product [for loosening] up rusty bolts" and beyond.

Amazon reviewers back that rating up, also placing it at a 4.7 out of 15,169 reviews. It's not hard to believe. No matter if you're working with plenty of room or not much of it, WD-40 has that handy built-in Smart Straw that gives you the option of a narrow precision stream or a wider spray. And although WD-40 is not exclusively a penetrating oil, there's nothing stopping you from believing the hype when it comes to loosening nuts, bolts, locks, valves, or other rusted hardware.

If all else fails, you can also try CRC Freeze-Off Super Penetrant on the seized bolt. This stuff has a freezing-action formula designed to crack rust instantly on contact. By chilling the metal via chemical reaction, the formula makes the rust layers crack and lets the oil work itself in faster and deeper. On Walmart's site, it's at a 4.7 out of 12 ratings. That's not a ton, but the reviews are nevertheless positive: Users call it the best thing ever, saying it works even better than putting heat on the bolt.

Amazon user reviews place CRC Freeze-Off at 4.4 stars out of 691 ratings, with some saying they didn't want to believe it'd work at first, but were proved wrong by the results they saw: "I was a little skeptical on buying this, but had some pretty tough bolts on a brake job. This stuff worked as advertised." Isn't that all you really want from a product? Redditors don't disagree: "CRC [Freeze-Off] has the worked the best even over [K]roil. It doesn't last long but man [it] gets down into stuff." A few others in the thread echoed something similar.

This list was created based on user reviews and community suggestions for the most effective penetrating oils. Products were picked based solely on user reviews on Walmart, Amazon, and Home Depot's sites as well as comments from users with hands-on experience across various Reddit threads.

From there, in order to narrow down the list to the top five you see above, we took some of the most common recommended products from Reddit and vetted them using verified reviews from Walmart, Amazon, and Home Depot. All the recommendations you see here are grounded entirely in users' experiences and based on their verified online reviews.