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Mousemilk is a special-use penetrating product. It good for freeing up frozen joints, etc. From their website “MOUSE MILK will dissolve rust, relieve friction and resist oxidation. MOUSE MILK has amazing creeping ability. Frozen nuts and bolts can be easily loosened and removed after allowing MOUSE MILK to creep down the threads and break up the rust and corrosion.”

It works really well on engine parts where heat and corrosion have almost fused parts. It’s not the first thing you reach for when looking for a penetrant, but it’s often the last. You can buy it from their site for $7.22 for an 8 Ounce Squeeze bottle. It also comes in larger sizes. SkyGeek has a bottle for $5.25. A little bottle will last a really long time.


From their website “An industry proven penetrating oil that has no equal. Quickly loosens rusted nuts and bolts – frees frozen shafts, pulleys, etc. Penetrates to 1 millionth inch spaces, dissolves rust, lubricates, cleans and prevents rust. Displaces moisture. The oil that creeps”

This is good for heavy duty corrosion. I’d use it on parts that look like they might be stuck, give it a few minutes, and then turn the wrenches. It saves stripping the heads and scraping knuckles. You can buy it from their site in a spray can AeroKroil (Kroil aerosol) for $11.00 per individual 10 oz. can. You can also buy a 55 gal. drum of it for $1,500 but that’s a bit of overkill. Amazon is selling a 10 oz. can for 11.50. It’s not available in my local hardware stores but I’ve seen it in large auto parts stores and you can get it from Aircraft Spruce.

PB Blaster

I’ve never used PB Blaster but there are lots of flame wars comparing this product to Kroil. One big advantage this has is that you should be able to find it readily at your local hardware store. It’s also relatively cheap, Amazon is selling a 16 oz can of PB Blaster Penetrating Catalyst for $2.84.

Pen Safe

This product is made by Frontier Performance Lubricants. From their website: “#853 PEN SAFE
A non-flammable fast acting penetrant, rust inhibitor and lubricant that can penetrate through rust and corrosion in as little as 15 seconds allowing fast and easy removal of rusted or seized components.”

This is a good first choice for just about everything that is stuck. Unfortunately, you can only buy it from the manufacturer, and only by the case. It runs $149 for a case.

LPS1 and LPS2

These are good lubricants and simple penetrants. LPS1 is a bit thinner than LPS2. You might want to use these before removing the wire from an aileron hinge. They are the penetrant of choice for unsticking and lubeing pulley wheels. LPS2 is great for lubeing hinges and rocker arms. They come in aerosol cans and in liquid that you can use in a spray bottle. They are made by LPS Labs.
From their website “Nondrying, oily film for long lasting lubrication. Loosens rusted and frozen parts. Protects against corrosion on steel parts indoors for up to one year. Displaces moisture. Safe on paint and most plastics.”

I’ve seen aerosol cans of LPS1 is in local hardware stores. An 11 oz aerosol can of LPS2 runs around $6.95 at SkyGeek and LPS1 is $11.95. A gallon of LPS2 is $27.95. I’d probably get a gallon of this if you do a lot of work on your airplane. Amazon is selling a gallon of LPS1 for $33.82.

Other Products

Some people use WD40 and Liquid Wrench but in my limited experience, the other products work much better.

Report from Machinist’s Workshop

BuckeyRat posted the following test on the TriumphRat forum.
Don’t forget the April 2007 “Machinist’s Workshop” magazine comparison test. They arranged a subjective test of all the popular penetrants with the control being the torque required to remove the nut from a “scientifically rusted” environment.

  Penetrating oil ......... Average load
   None ..................... 516 pounds
   WD-40 .................... 238 pounds
   PB Blaster ............... 214 pounds
   Liquid Wrench ............ 127 pounds
   Kano Kroil ............... 106 pounds
   ATF-Acetone mix.............53 pounds

*The ATF-Acetone mix was a “home brew” mix of 50 – 50 automatic transmission
fluid and acetone.*

*Note the “home brew” was better than any commercial product in this one
particular test. Our local machinist group mixed up a batch and we all now
use it with equally good results. Note also that “Liquid Wrench” is about
as good as “Kroil” for about 20% of the price.

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