I just read in the vendors section of Cosmoline being used to coat a transmision for protectiveness after being cleaned.. Has anyone used this before? How does it hold up? (apperently it is used for fire arms and automotive, available in aresol and bricks)

Curious as I recently replaced my transmission and now have a very cleaned case..


Cosmoline is the trade name for a generic class of rust preventatives, conforming to MIL-C-11796C Class 3, that are a brown colored wax-like mass; have a slight fluorescence; and have a petroleum-like odor and taste (as detected when working with it).

Chemically, cosmoline is a homogeneous mixture of oily and waxy long-chain, non-polar hydrocarbons. It is always brown in color, but can differ in viscosity and shear strength. Cosmoline melts at 113-125 °F (45–52 °C) and has a flashpoint of 365 °F (185 °C).

Its most common use is in the storage and preservation of firearms. Previously, cosmoline was used to preserve other items. Entire vehicles can be preserved with cosmoline.

As a protectant against what? As you mentioned it is waxie and thus would attract a protective layer of dust. If a protectant was required I would consider a spray-on anodizing agent. IIRC, I bought some from Aircraft Spruce years back. It is a lightweight alternative to primer used primarily on aircraft aluminum. It leaves a nice light blueish tint on the metal. If interested I'll find the name of it for you.

There are different types of cosmoline. The old stuff you used to heat up and apply, and it stays tacky for a long long time. The newer stuff that we use here is the Cosmoline brand, in a spray can. It does dry to a waxy hard finish, but it takes a couple weeks for it to really get to that point. LPS#3 dries as well, and may be a little less nasty than the cosmoline. I would worry about some chemicals on the case, since the case may be MAG not alum, this i'm not to sure about.

The thing with Cosmo is that when you actually put the thing into use that has been protected with it, all the cosmo has to come off. Be it firearms or cars or whatever.

And removing cosmoline SUCKS. Especially on old rifles where it has soaked into the wood. Leaving it on your transmission would cause it to slowly melt and drip on to your heat exchangers. Which would then cause smoke and stink and stinky smoke and maybe fire. it will also drip on your garage/driveway causing slick spots.

But it does to a good job at stopping rust while in storage.

How do you get the Cosmo off parts that have been stored in it for a few years ? I have a new flywheel still in the original box and it is covered with Cosmo..

Mineral spirits

I get it!! Long term storage protection, .. I thought the melting point was fairly low..

Oh, this one I know. Every new machine tool that came in had EVERYTHING covered in cosmoline. Mineral spirits is correct, but the best out of all the mineral spirits I found was Kerosene. Spray, soak, wipe off. Or in my case a plastic putty knife. Thank god they started using grease now.

This is a good topic and has been covered at various times, even in this forum IIRC.

Here's Tectyl. It's the stuff that Porsche used and your transaxles came with this. I think 553 is the closest to our original coatings.

http://www.mil-specproducts.com/productPage.aspx?prodID=446
http://www.daubertchemical.com/main.taf?er...productLineId=1

Otherwise, there are several other alternatives. The best one I've seen is

http://www.pexa.co.uk/french/pdfs/TDS_Socopac_65H.pdf

Then there are easier ones to get, like this one...

http://www.crcindustries.com/ei/content/pr...N=10200&S=Y

I like this one better than the other CRC (above) but it's working temp is right on the edge.

http://www.crcindustries.com/ei/content/pr...N=06026&S=C

For those interested in a technical discussion...

http://www.finishing.com/faqs/magnesium.html
http://www.sintef.no/static/mt/norlight/IC...-Skar_Hydro.pdf
http://www.indestructible.co.uk/rockhard/MAGPR2.html

Good luck!

Having cleaned cosmoline off a few rifles, I have found that boiling water works better than mineral spirits (and is much less smelly).

I'm thinking that on a transmission one could easily get the cosmoline off with a pressure washer (especially one that uses hot water).

You don't have to be nearly as delicate with it as you would an old rifle (and there's no wooden parts of the tranny to soak up the water you're cleaning with).

I clean the transmission case with engine cleaner and then brake cleaner. For the best finish I then clean the case in my media blaster with crushed walnut shells, and then seal it with clear high temp spray paint.

For cleaning off cosmoline I use DuPont Prepsol or Acme Klix88. Of course brake cleaner melts it off very well.

I am not sure, but you might be referring to my recent post in the vendor section. I mention that I use Tectyl to coat transmissions that are cleaned as part of my rebuild process.

Magnesium does oxidize so that is why bare Magnesium needs to be protected. Like aluminum, it does create a thin layer of oxidation. But while Aluminum Oxide is very strong and prevents additional corrosion, I don’t think that Magnesium Oxide is very strong and doesn’t provide as much protection. So you will see Magnesium corrode away much faster than Aluminum. I also suspect part of the issue is where Magnesium falls on the galvanic chart. It is below Zinc, so it makes a perfect sacrificial anode and corrodes away before other metals such as steel. Hot water tanks usually have a sacrificial Magnesium anode to prevent corrosion of the steel tank and fittings.

I need to post a photo of a case I just took apart. The differential cover (on the inside) has a deep bit of corrosion. I would like to talk to a chemist or metallurgists about this, but I suspect it might be something like how mercury is the arch-enemy of aluminum. If you have not seen this before, you should watch how mercury prevents that thin layer of Aluminum Oxide from stopping additional oxidation.

http://www.youtube.com/watch?v=Z7Ilxsu-JlY

I suspect that something (maybe mercury?) has a similar effect on Magnesium. Sometimes you will see an area that is fine and right next to it deep corrosion as if something broke that Oxide barrier. Some people call that "worm" corrosion as it looks like a worm ate holes or paths in the Magnesium.

Anyhow, if you don’t use something like paint or a modern aerospace coating, your transmission case will slowly corrode over time if left unprotected. When I rebuild a case, I clean it for my customers. While a greasy case does provide some level of protection, every case I have seen has some level of corrosion going on even when covered in grease. Basically I don’t believe in leaving it greasy as a way to protect it. Paint or a spray on coating is much better at coverage than incidental grease.

By default I do not media blast and then paint the cases I work on (this can be done at extra cost.) But as part of a normal rebuilt, I clean and then spray with Tectyl which is a Cosmoline “like” product. “Cosmoline” is just a trade name of a Mil Spec waxy coating (Sort of like how “Xerox” ended up being a generic name for photocopy.) Tectyl is the brand that was used by the factory to protect the assembled transmission. I was able to source some, so that is what I am using as well. I figure if it was good enough for the factory, its good enough for me and my customers. Event today there are various Tectyl products aimed at the automotive industry.

Regarding how well something like Tectyl lasts, I have done some testing on this. Any spray on waxy coating is not going to last forever. If exposed to the elements it eventually gets worn away. Nook and crannies as you would expect last much longer, but the coating on edges and ridges in the casting wear off first. I have run some tests and I would say that the coating provides protection in the “months” range and not in the “years” range. I would go beyond a year, but my test case hasn’t run that long yet.

While I use Tectyl, I think the CRC Marine Heavy Duty Corrosion Inhibitor is good stuff as well and is probably easier to find. In fact, I suspect it might be a Tectyl clone, or even a repackaging of Tectyl.

You can clean this stuff off with Brake Cleaner or Mineral Spirits.

I'm interested. I've been getting set up to do the walnut shells and high temp clearcoat with my transmission rebuilds. Clearcoat is simple and keeps oxygen out, and the transmission looks shiny when you peek under the car. Then you don't have drippy goop going all over the place (heat exchangers, exhaust, etc) later and stinking up the area.

I would not want any paint put on my aluminum tranny unless it is a two part paint. I would need to study up on magnesium to know whats good there.

While I may be getting set up to do the walnut shell routine; that's exactly why I don't have a set 'standard' of how I do the finishing touches on transmission rebuilds.

Everyone has their own opinion on how they should be done. I'm happy to rebuild a transmission and make it shift nicely, and finish it however the customer would like it. What I prefer might not be what someone else prefers.

Its a tough problem because there is tons of different opinions as to what to do. There is everything from do nothing, to rattle can paint, to coatings (some of which work via chemically converting the Magnesium surface) used by the aerospace industry.

Just like Jim, if a customer wants me to do something different than my standard rebuild, I can do that. Untouched, coated with Tectyl, painted, etc. All are up to the customer to decide.