Kroil and let set. Solary Magnetic Induction Heater Kit 1000W 110V Hand tool. I've let set and reapplied every week

pb blaster works well. heating things , start slow and try it if it doesn't move on the first ugga dugga try more heat. if its really stuck  nice cherry red but don't melt it. Sure some solvent's will burn penetrating oil, grease , caked oil but wont be a fire ball. ventilation is key for brake clean due to the vapors so give  that a lil time before torching if you just cleaned something off. washer fluid basically lights like gas too . Obviously shit still breaks and the best way to learn how to deal with drilling straight at weird angles and tapping is being forced to do it. Impact ,power, air tools will break rusted things that may have just come out by hand.

Lost of methods of dealing with rusty fasteners, which ones you use often depends on your abilities and what tools you own; for example it's difficult to weld on a nut if you don't have a welder.
WD-40 is intended to displace water on metal parts prone to corrosion - the WD stands for Water Displacement. It is NOT a penetrating oil, yes like any lubricant that contains a solvent it can sorta function as one, but it's far better to use a real penetrating oil like Kroil, CorrosionX, PB Blaster, home-made ATF and acetone mix etc.
As far as what method you use when; my rule of thumb is to always start by cleaning off the loose rust around the fastener with a brush or wire wheel and then use penetrating oil for a day or two. Use proper fitting wrench, socket, bits etc., often helps to tighten the fastener as well as just trying to loosen it, twisting it back and forth often helps to get a fastener to unscrew. If I have the access I use an impact driver on a screw, the pounding does help loosen rusted fasteners but often you don't have the space to swing a hammer. Battery or air impact wrench can be an option on larger bolts, or if you want to break the head off a smaller bolt. The smaller 1/4 impact drivers can also be used to vibrate a bolt even though they don't have the power to remove the bolt. Be careful with them as they do now have enough power to twist off smaller bolt heads. After all attempts to loosen a fastener with the proper tools fail then go to heat, I have a propane torch for plumbing duty that usually works and a heat gun for times when melty stuff (plastic, rubber etc) or burny stuff (like a fuel line) is close to the fastener. Yes a torch usually will set the penetrating oil on fire, sometimes that is really bad, a lot of the time it really doesn't matter as most of the oil has already dripped off. I always try really hard not to strip out the screw head, round off the bolt head whatever; if you can't get a good grip on what you are trying to turn then you can't break the fastener as a last result to remove whatever it is holding and then use vise grips or weld on a nut to remove the rest of the bolt, screw etc. Sometimes this can be the second option (first is just using the proper tool), like exhaust manifold bolts. Many mechanics will just break the bolts if they don't come out easily, remove the manifold and then deal with the stubs now sticking out of the head.
Some methods are specific to the type of drive head the fastener has, you can use the next size larger torx bit pounded into a stripped allen head bolt to try and get it to move. Or if you have an air hammer you can use a chisel bit in it to cut a slot into the rounded off bolt head, and unscrew it using the air chisel as a screw driver. I suppose it's possible to also do this with a cold chisel and hammer but I haven't been successful with the hand tool option. Last resort you can use an air hammer to cut off the head of the bolt or screw and then use vise-grip pliers on the bolt stub sticking out. If it's a thin flange being held to something this doesn't work as well as the stub is so short; but it may be your method of last resort.
Edit: Need to add left hand drill bits to drill out bolts and screws, works much better than a right hand drill bit followed by a screw extractor.

Heat is the best thing I've found. Touches and inductors usually get the job done. I have used many different penetrating oils and haven't noticed a significant difference in any of them. I have wd40, PB blaster, ion from BG, and several others at arms length in my shop at home and work. They all do about the same.

Use MAPP gas instead of propane, burns much hotter and wind blows it out much less. Whatever solvent you spray will catch fire but it's not a big deal, I keep a spray bottle with water in it and a fire extinguisher handy, the water takes care of everything up until OMGWTFBBQ. I've only used a fire extinguisher a couple times and that was when torching entire cars apart.

Project farm did a test on penetrating oils, and found liquid wrench to be the “most effective “ in his tests.. for really stubborn shit, you need fire.. It can’t stay stuck if it’s liquid

Do I get to be the first to say, "it depends"?

If it's an aluminum and steel fastener joint, heat is a must-have. Heat and slow steady pressure seem to work on these galvanic corrosion issues.

Steel on steel? Good penetrant, heat if you have it, and lots of mechanical action (back n' forth) if it's not torqued to a bazillion pounds.

Is the joint locked due to 'thread additives'? Loctite uses heat to your advantage. Gravel-road dust is a bitch beyond compare, but water helps get it apart. Loose rust is back to heat and repeated applications of oil to flush the loose rust out.

Stainless on stainless galling, or aluminum on aluminum galling? You're just in trouble, no way around it. This is where I recommend material removal (i.e. drill it out). If you ever get the chance to thread an aluminum bolt into an aluminum part, just punch your computer monitor now to know what it feels like.

Heat is a relative issue. If it's rusted exhaust components or steel brake line fittings, getting it borderline red-hot is about the only choice. For aluminum, localized propane is all you need.

The most important thing I've learned with rusted bolts is the loosen-tighten-loosen method. Obviously still use penetrating oil and possibly heat, use good fitting tools and clean the fastener head. But even with all those things you can easily snap a bolt if you dont work it back and forth a few times first.

Hey Kitties. Worked on lots of rusted bolts, so this is one area I can help.

1) Kroil is about the best penetrating oil I've ever used (and it actually smells good, lol). Has worked way better than WD40, PB Blaster, Liquid Wrench etc.

2) a good impact wrench is actually a lot more effective for rusty bolts than a breaker bar. The impacts are more effective at breaking the rust bonds, to 'unstick' the fastener. I've broken more fasteners with a breaker bar than with a high torque impact, and I've used everything from the at-the-time strongest pneumatic impact that Ingersoll Rand made, up to the current strongest cordless Milwaukee M18 impact (which has more torque than that pneumatic).
3) I've used heat and cold for really stubborn, rusted fasteners.
Which to use (heat or cold), where and when:
- simple; metal expands when heated, and contracts when cold, so you want to heat what's outside, and cool what's on the inside (i.e. I don't heat the bolt. That's making it expand inside the part it's screwed into).

Again, the aim is to break the rust bonds/stiction, and even a tiny difference in the dimensions can do it.

My usual process for working on my own stuff (i.e. not a business with time constraints) when I come across a stubborn/rusted fastener:
- blast the fastener liberally with Kroil, and let it sit for at least 15 minutes (or even overnight).

- hit it with the impact wrench

- if that doesn't do it, another blast of Kroil and hit it with the impact again (depending on the wrench, you'll eventually get a feel for how many ugga duggas risks snapping a bolt of a given size, and learn to back off before that point. Also, lots of the newer cordless impacts have selectable torque ranges,  so you can select the lower torque settings to reduce the chance of snapping fasteners. The Milwaukee also has a variable trigger, i.e. you can use a light squeeze for slower speeds/less power or a full trigger squeeze for Maximum ugga dugga).

- if that fails, THEN I use heat/cold. Oxy torch, propane torch, MAPP gas torch (the new MAPP doesn't work as well as the old versions. Old formulation was a lot hotter. Newer stuff in the last few years is not that much better than propane), can all work. In tight spaces, those mini butane torches/jet lighters can work, though more slowly.

Heat up what's outside (the part the bolt is screwed into), then hit the bolt with a 10 second blast from an inverted can of canned air (you can buy these at Office Depot etc. For blowing dust off electronics, but if you hold the can upside down, it'll spray the propellant which can rapidly chill metal enough to create frost). Blast Kroil at the interface and immediately hit it with the impact again. Has never taken more than 2 cycles of this to break something loose.

*** for nuts, obviously you heat the nut, since it's on the outside.

Yes, for nuts, you wire brush the stud to clear as much rust as possible, blast with Kroil and you heat the nut (then if you have the canned air, you can blast the stud to freeze/contract it)  before hitting the nut with the impact wrench

While the nut will expand in all directions, it has the ability to expand around the stud, unlike heating a bolt that's constrained inside the part it's screwed into. (You can actually test this yourself with a clean bolt and nut. Use thermal protection. Torque the nut onto the bolt. See how easily it unscrews. Torque it on again, then heat up the nut before unscrewing it again).

Again, think of it as breaking the rust bonds by making tiny changes in the dimensions between the threads. Think of rust as a bonding agent that hardens (unlike gummy bonding agents that remain sticky). The moment you break that bond with even a tiny change in the interfacing surfaces, that bond is broken (though the remaining crud still results in increased friction with threaded fasteners).

The loosen-tighten-loosen someone mentioned above is another way to attempt to break the rust bonds (but an impact is much more effective. The repeated 'shocks' from the impact wrench can break those rust bonds before overtorquing the part).

The other objective of the tighten-loosen-tighten is to allow some of the rust/crud to move (i.e. on a badly rusted fastener, as you turn in only one direction, even after breaking the rust bonds, the rust can 'load up' in the threads. Tighten-loosen-tighten allows you to carve through and clear that crud rather than have it progressively packing/loading up).

Ah. The listing said 330 ft-lbs which is pretty low for anything more than smaller fasteners (especially if they're rusted), but yeah, the bigger ones are ~twice as heavy.

Any way to use impact rated extensions to be able to use the big one? I've done that for some hard to reach fasteners; 9" impact extension to impact swivel adapter to impact socket.

That's the awesome thing about the internet; it allows a bunch of people to easily connect and exchange info in differing areas of experience/expertise.

While metal does conduct heat, it's about the difference in the rate of thermal transfer (which is why the hottest heat source is the most effective. You want to heat the nut faster than the nut can heat the stud. With a high heat source, you can. With a lower/weaker heat source, there's less differential because it's taking more time).

If I'm heating a nut, I DO try to heat all sides of the nut if I can reach it. If you have a high heat source like an oxyacetelene torch, it's easily visible (if you heat just one side, you can make just that side red hot, or even cut/melt that side. BTW, you DON'T need to get a fastener red hot. You just need to heat it enough to change the dimensions of the interfacing surfaces).

That said, if you can't get all sides, changing the dimensions on one side can still help enough to loosen a nut that wouldn't loosen previously. That's also why I always use heat and cold in conjunction. Heat the outer part, then use the inverted canned air with the 'straw/tube' to rapidly chill/shrink the inner part. Squirt a little Kroil (it'll work its way quickly into any tiny gaps created by the expanding and contracting) and immediately hit it with the impact wrench.

It depends on the fasteners. More power can remove fasteners more easily, but can also break smaller fasteners more easily.

One advantage I hadn't thought about for the pneumatic impacts is that they're generally lighter (and smaller), since they don't rely on the battery for power.

One thing that I’ve found to be helpful is bees wax and heat. I’ve used it on steam pipe flanges that were 50-60 years old and it loosened nuts that I couldn’t loosen with cheater  bars or impacts.

Wire brush the threads to remove all the loose rust then heat the nut/bolt/fitting up. Once it’s hot press a piece of beeswax on it until it melts and soaks in.  Then try to remove. The nice thing about this is that you can easily get enough heat from a propane torch to do what you need and you don’t need to worry about chemicals on the ground or the floor if that’s a concern.

There is no one size fits all for stuck fasteners. You just learn from experience what works best for the situation.

I use crayons for that too, I've gotten some odd looks about having a pack of Crayola in my tool box.

Just tell them you’re a Marine!!

Lots of good advice already so I'll just add, make sure you are using a six point socket to avoid rounding off the nut or bolt you're trying to remove.
If you're using impact sockets they should be six point, but I know that not everyone has impact sockets. On rusted nuts and bolts the shoulders are often somewhat compromised, and a twelve point socket will likely round it off.

Kitties, since it's you, if you are heating lug nuts on an inflated wheel/tire combination.  Out of an abundance of caution I will suggest you be sure to remove the valve-stem core to eliminate any chance of heat migrating to the wheel, increasing the tire pressure resulting in a tire kaboom.

Granted there is probably more than enough heat dissipated through the lugs, hub and drum to prevent that.  This is more a precaution for welding on a rim with an inflated tire but still applies.  I don't want a million in one shot to catch you.  

It's easy enough to reinstall the core and reinflate the tire when you are done.

I have hit bolts/nuts with a hammer or A brass punch.
The vibrations can help loosen them.

Also now use silicone on the threads and bolt head if I can get to them.
City uses calcium chloride and it rusts/corrodes shit fast.

MI: part of the snowbelt saltbelt.

Nowadays, if I remove a fastener that has any rust on it, I wire brush the threads and apply Silver antiseize when putting it back on.


P.S.
Forgot to mention;
For anyone using heat to remove stuck fasteners

Take into account that the application of heat will potentially remove/destroy any heat treat originally used in making the part.

Metallurgy 101: for a given composition of steel (defined as iron + carbon, and usually several other elements in combination), you can alter the properties of the steel by varying the heat treat.

The various properties of steel are generally classified as
Hardness
Toughness
Strength

If anyone watches the show 'Forged in Fire' they'll probably have seen evidence of poor heat treats (making the metal too brittle, too soft, too weak etc.)

Engineers tend to design things with a built-in safety margin, i.e. the size (and number) of fasteners used for a part should be able to withstand multiples of the actual forces likely to be encountered in regular usage.

That said, when you heat a piece of steel red hot, you've effectively removed any heat treat, potentially compromising the strength and the amount of force that particular part was originally made to withstand. At what temperature below red hot do you begin to risk removing/compromising the heat treat? That depends on the steel, and the heat treat originally used. If it's a critical part, best practice is to replace it with a new part if it took a significant amount of heat to remove (and as mentioned, especially if you got that thing red hot).

I know, I know, there will always be folks going, "I've done that loads of times and never had a problem". YMMV. I prefer to make informed decisions, based on as much knowledge/info as possible, so having said all that, now folks can consider and make their own choices.

Sometimes a breaker bar with a length of pipe slipped over the handle will give leverage.  I've used some really big pieces.

Silicone caulk.

Not the antiseize grease used on brake pad backplates etc.

This stuff



Good to 1600f (I've even used it on exhaust flange and hanger bolts, which always get rusted to heck on Winter street driven vehicles, from the salt).

I also use it on lugnuts and other bolts and nuts where I find any corrosion.

Here's another consideration and a long'ish explanation of why I'm not too concerned.

Applying any substance like grease or antiseize alters the torque spec if it wasn't spec'ed with the substance/lubricant, because it usually decreases the friction, so with the same amount of torque, you're potentially torquing it further than spec.

So here's the long'ish explanation:
Contrary to what a lot of folks apparently think, threaded fasteners rely on the clamping force provided by the elastic stretch of the stud/bolt.

Think of the threads as dozens of ridges between the two mating objects. As you torque the fastener, it causes the stud or bolt to stretch elastically (a very tiny amount). That elastic stretch induces the force  distributed between the ridges of all those mated threads, and is what provides the clamping force to hold the parts together.

Elastic deformation = good. That's what provides the clamping force holding the parts together.

Plastic deformation = bad. The fastener has been overtorqued and plastic deformation is permanent. The fastener is compromised and can no longer provide the amount of clamping force necessary, because it's too weakened to withstand the force it's supposed to withstand under elastic deformation.

Back when I was still involved in auto racing, we'd use a bolt stretch gauge to measure the exact amount of bolt stretch to know that the fastener was optimally tightened (tensioned elastically. Using a torque wrench is a kludge that approximates this). These bolt stretch gauges used to be mechanical, and require you to have access to both ends of the bolt (i.e. they were used mostly for the connecting rod bolts and head studs).

Then they developed ultrasound bolt tension/stretch gauges that work by touching the transducer/sensor to the bolt head. The transducer sends an ultrasonic signal into the bolt and can messure the bolt length to 0.0001mm based on the delay of the signal bouncing back from the opposite end of the bolt. When we got one of those, my nerd OCD led me to measure all sorts of things

I found that for a lot of fasteners, the amount of 'over'torque when using a non-approved substance (eg. Antiseize on lugnuts) was well within the design overspec. The reason I began using it on my lugnuts/lug bolts, was because of snapped lug studs on wheels when I took my personal vehicles to get new tires. Some of these shops would way overtorque the nuts, and some would use a 4 foot breaker bar on overtight (or rusted) lugnuts.

Since then, after getting new tires installed, I remove the lugnuts when I get home, apply Silver antiseize, then torque them back to spec. Since then, I've never had any further issues and the lugnuts are never overly difficult to remove. Same thing with the rusted exhaust flange bolts on an older vehicle (that were a PITA to remove). After using Silver antiseize, when I removed those bolts again a couple years later, they came off easily).

Doesn’t help you now, but I use this stuff on my car to prevent corrosion. Cor-ban 35 It’s sorta like paint, sorta like gel. It’s very slightly sticky but not greasy, and won’t wash off.

About $20 a can at sky geek.com
There may be better or different stuff out there, but that’s what I use, and it works.

Yep, that's pretty much the same stuff, just different brand and packaging.

Along those lines, this stuff has only recently become available in the US




Various folks have done their own independent testing and it's one of the most effective corrosion protectants out of all the available options (last test I looked at compared 30+ products).

Just about anything that holds good or is in stock here in Bush AK is what I use.

I have used this before.
Put some on the threads and bolt head after you are done.
https://www.amazon.com/dp/B0001FFLUI?tag=arfcom00-20