Liquid Wrench, PB Blaster, other penetrating oils -- for many years I have been using them with the assumption that they have some acidic, or otherwise corrosive component, that breaks down corrosion. Not sure how I arrived at this idea, no doubt someone else told me. And I've never thought they should be left as a final lubricant, or that not applying some other lube would leave ferrous metal in jeopardy of some long term damage from them. Is there any truth to this, or am I just wrong (again), and these penetrating oils work through some other action?

Never heard anything about acids. But your hands have acids on them and some claim that enough to damage bearings if you don't wash your hands before handling them. I don't keep up with it now, but when I was young, that was a common position in the aircraft mechanic conversations and racing circles. This was before the days of computer bulletin boards and forums.

Since you are asking about all, then I won't say for certain, but I doubt most use acids. They just have a particular formula of oils and modifiers that help the oil penetrate and spread instead of staying in a blob.

But since they are so light, obviously their lubricating properties may not be adequate for the part you put them on. Then the question becomes is there enough of the thinner penetrating oil left to dilute the other lubricant significantly or will the coating of penetrating oil prevent the grease from clinging to the bearing surface and doing what it is supposed to do.

Most of the website for those penetrating oils have a good write up about them. sometime you have to dig a little and even look at the MSDS data or such.

And don't forget about Kroil. Sometimes it works when the others fail.

Penetrating oils are just a low viscosity oils. Nothing corrosive in them. Most rust and corrosion has a lower density than the metal it forms from so the oil penetrates into the threads and lubricates them. This allows the parts to be separated because they can now slide past each other.

Iron oxidation (aka "rust") has a very porous nature so the oil can penetrate into it better than other kinds of oxidation. Rust is also softer than the metal it is formed from so it tends to break when force is put on it. If the iron parts can slide past each other, they can come apart easier.

Aluminum oxidation products, for example, are extremely hard and many even be nonporous. Think anodized aluminum. The aluminum oxide is also much harder than the underlying metal so it doesn't break and slide as easily. Penetration oils often don't work on aluminum parts for this reason.

You could leave the oil in place as it will still lubricate but the oil is so low a viscosity that it will eventually flow away or evaporate. Putting something like grease on the threads after you've gotten them apart will go a lot further towards keeping the parts from welding back together.

I have a 70s British sports car with chrome and stainless wire wheels. Every year before winter storage, I coat the wheels liberally with WD-40, and leave it so all winter. I bought those wheels in 1995, they still look new. Never heard of any instance of WD-40 actually harming metal surfaces. Not sure on PB Blaster, my first choice on seized hardware.
Tim

There are "penetrating oils" that are more than low viscosity oil. "Ed's Red" was developed as a target rifle bore cleaner but has a great reputation as a penetrating oil. It's an equal volume mix of Kerosine (or OMS), Dexron ATF and Acetone. However, as noted above, no acids of any kind.

Cyccommute's answer is way better then mine. I'd go with that. Tim

Kroil is my first choice, I don't even bother with the others.

Sometimes I have come up with these ideas, and hold on to them forever, and have no idea how I got them. Sounds like this one is wrong. It's good to know -- I may have avoided using penetrating oil for this reason, and didn't need to. Thanks, folks.

i use a light coating of PB to remove/reduce Aluminum oxide on parts all the time... no ill effects, and the parts look MUCH BETTER!

Try getting the Product Safety Manual print out for them , it should list whats in it.

Thanks again -- looked up the MSDS for Liquid Wrench, PB Blaster, and Aero Kroil. Under ph, for each of them, it said N/A -- so, obviously not an issue.

Not exactly sure what you are asking, but from my experience, penetrating oil do nothing to "break free" seized bolts, seat posts, ... but once free, the oil helps lubricating the parts, for easier disassembly.

In these cases, I sure that the NA means "not applicable" rather than "not available". They would have no pH since they are neither acidic nor basic nor can even ionize.

I noticed over many threads your answers are always very thorough, scientific and spot-on. Sounds you have a good engineering and science background. I sometimes find myself scrolling through a thread to your reply because it usually resolves the whole problem.

PH is based on water. Since the lubes have no water (thus anhydrous) , there is no pH.

Agree. A class of Al2O3 is called corundum. And beryls, rubies, and sapphires are all in the corundum class. Also, the grit on most sandpaper is corundum.

BTW, in at least one test (and I don't think its apochryfal), a 50:50 mix of ATF and acetone worked better than any pre-made product. But the acetone will strip your paint. I think a product called Kroil was the best commercial penetrating oil.

The WD in WD-40 stands for "water displacing formulation #40" It was specifically developed to get and keep moisture out of equipment. It's fairly ineffective as a penetrating oil except in relatively undemanding circumstances.

It's also great as a cutting lubricant /coolant when drilling, taping and machining aluminum. (just don't make the mistake of using it on steel particularly with a tap!)

BITD I ran a ceramics plant. We had lots of water around machinery so used a lot of it. I had to keep it locked up because it kept disappearing. Turned out some of the older women on the lines though it was good as an arthritis treatment.

They'd heard it fixed squeaking joints.

Best penetrating oil I ever got my hands on was some sort of aircraft hydraulic fluid that was repackaged and sold as penetrating oil. That stuff was like magic so of course you can't get it anymore.

Liquid wrench seems to be about as good as there is out there now. Also works as a tapping fluid for steel and stainless steel. Not as good as the old Carbon Tet based fluids though.

Introduced to Kroil a couple of years ago. THE BEST - darn thing is it's been around forever

And of course, the VERY best penetrating oil by far, a mixture of 50% ATF & 50% Acetone.

And of course, the VERY best penetrating oil by far, a mixture of 50% ATF & 50% Acetone.

+1 for Kano's Kroil. The best there is. Is also the best gun bore solvent made. Lifts lead and copper residue off of a gun barrel in one swipe by breaking the bond from the metal of the gun barrel. It is not an acidic chemical.

Kroil also works well on spoke nipples that are stuck or cotter pins on cottered cranks, stuck nuts, etc.

Patience, Dan... Patience...... and there's a point of no return for rusted stuff...

I haven't had much joy with that far as seized stems go

So far I have been lucky but on the rare occasion that penetrants have not worked, I have always had success with carefully thinning the wall of the stem with a drill and PATIENTLY using a hacksaw blade to further weaken the walls of the stem until it comes free.
Works with alloy stems and with alloy seat posts..... but i have never had to try it on steel.

Bink

My last resort is to shock it heating it with a torch gun then squirting it with WD-40, Binky, especially when stems want to be saved {works everytime!

I have an issue with a Miyata frame though atm that got given to me, he started sanding the frame down but couldn't get the seat post out, cut it flush to the seat tube, lol, dang
drilled a hole on the back where you can, fed a wired rope through, and hitched it up to a tree and my towball, broke the damn wire so upgraded to a stronger one then broke the rope on the towball, upgraded that to a chain then broke that other wire

i may need to use your method or dissolve it with caustic soda