Removing a stuck bolt is a frequent cause of frustration among automotive enthusiasts and professional mechanics alike. Over time, bolts and the parts they mate to tend to rust, eventually making bolts extremely difficult to remove. This bond can become so strong that the bolt head or shank isn’t strong enough to transmit the torque required to loosen the offending bolt, resulting in the worst possible outcome: a broken bolt. This is most commonly seen in areas subject to extreme heat cycling (heating and cooling) such as your exhaust header and brake components. In the best case, stuck bolts can be a huge waste of time and a big pain that requires use of an easy out and a drill. More severe cases require potential drilling, plug welding, and retapping the hole. If you don’t have the skills to do this yourself, it can be costly.
The first line of defense when removing a frozen bolt is to grab a breaker bar. Tapping the head of the bolt softly with a hammer can loosen up some of the rust which can sometimes enough to get the bolt loose. However, you must exercise caution with this method as it’s easy to break bolts this way if you don’t break the rust up. When this fails, it’s time to get out the rust penetrant (although it never hurts to spray a shot before trying to remove a bolt with your breaker bar).
The best rust penetrants are typically aerosol products that you spray on and around the head of the bolt or nut in question. As you spray, they slowly seep into extremely tight spaces and work to break up rust as well as lubricate the threaded surfaces of the bolt and the mating part. After spraying and waiting a couple minutes, a quick twist with your breaker bar usually has you on your way.
The Best Rust Penetrant
When it comes to selecting a rust penetrant, there are lots and lots of options. We have reviewed the two we use most often below.
WD-40 Rust Release Penetrant Spray
Our favorite is the WD-40 Rust Release Penetrant Spray. WD-40 has a long standing reputation for creating lubricant sprays that cater to the automotive world, machinist world, and many more. In fact, there is a reasonable chance that you have at least one WD-40 product in your garage right now.
The WD-40 Rust Release Penetrant Spray works with excellent results. After spraying it, we recommend that you let it sit for a few minutes before trying to remove your bolt or nut. While you are waiting, the WD-40 slowly seeps into the tiny cracks and crevices to attack the rust to free your fastener. Furthermore, it provides lubricating properties to your threads in the future which can potentially cut down on sticky bolt issues. The WD-40 is plastic, rubber, and metal safe, so it is safe to use around most car parts. That said, we always suggest exercising caution when using it near your paint.
The final thing that we like about this product is that it has a permanently attached straw which allows you to direct the flow of the liquid precisely. Most penetrants come with removable straws, and these tend to get lost over time which can become annoying. Overall, you can’t go wrong with WD-40’s penetrant spray for releasing stuck bolts.
Blaster 16-PB Penetrating Catalyst
Another longtime standby in our garage is the Blaster 16-PB Penetrating Catalyst, which is most often referred to as simply PB Blaster is most automotive circles. PB Blaster has been around since the 50’s, and is found everywhere from auto shops to military vehicle depots. It’s rise to the top has been a combination of excellent performance as well as some pretty smart branding over the years. They also offer a full lineup of various types of lubricants which make their name pretty well known.
PB Blaster works in much the same way as the WD-40 by seeping into micro cavities to break up rust to free your bolt. PB Blaster is non evaporating, which means that it will stick to your threads after you have sprayed it, which allows it to lubricate your threads upon reinstall. While they don’t specifically advertise it, we have found that this tends to cut down on the amount of future stuck bolts.
Overall, if debating between the PB Blaster and the WD-40, from a performance standpoint it’s a toss-up in our opinion. As far as the best rust penetrant goes, they are pretty dead even. If you like the idea of the permanent straw and are willing to pay the extra buck so you don’t have to search around for it when it goes missing, go for the WD-40. Otherwise, pick up a can of PB Blaster. You’ll be happy either way.
When it comes to freeing stuck bolts, there is no more effective way than to hit it with a shot of rust penetrant oil before trying to remove it. We recommend that every mechanic have a can on the shelf so that they can grab it if they get into a tight spot. While these are our favorites, there are plenty of other options out there too so feel free to have a look by clicking here if these aren’t quite what you are looking for. Happy wrenching!