TPL

Synthetic aircraft grease = VERY, VERY HIGH QUALITY STUFF

Aircraft face a huge number of atmospheric conditions ....an aircraft cannot just 'pull over' when a mishap occurs

gfk_velo

Gently and with great respect ...
"Aircraft quality" in this context is utterly meaningless.

Are we talking about the grease that is used on the sliding drawers in the galley, or are we talking about a precisely formulated grease used for a specific purpose in essential system in the aircraft (in which case, it will be produced or selected for a range of quite specialist purposes).

A bit like "aircraft quality carbon composite" - is that the stuff that is used for the light switches, or the stuff used to skin an F22?

Not trying to pick a fight but marketing vs accuracy is always an interesting conversation ... which is kind of the point of our notes that we use for students.

gfk_velo

This is a huge subject, one in which I've become interested because I'm a born skeptic ... I wanted to drill down (if you'll forgive the almost-pun) into the back story of oils and greases.
I read so much in marketing waffle that just didn't seem to add up, so gave myself a crash course in the chemistry of oils and greases (thank God for Foundation Chemistry on my degree course).
Here's quite a good overview article, to get you started, I'll warn you though, as soon as you start following the links, it gets to be pretty deep water, pretty quickly:
https://knowledge.ulprospector.com/8...ner-structure/

sincos

Thanks, that clarified a lot (but made other things more mysterious).


In the (probably remote) event anyone else is interested, here's what this grease newbie learned. Grease is an emulsion of oil and thickener ("matrix" would be a better term) but mostly oil and is characterized by shear-thinning. Shear strain on the grease releases the oil, which is what actually does the lubrication and why the viscosity drops dramatically under shear, and the "thickener" reabsorbs the oil when that strain is relieved. The shear-thinning is why thickeners are soaps or detergents and not wax or petroleum jelly: the micellular nature of the thickener acts as a sponge to release and reabsorb the oil. A wax thickener would just thicken the emulsion and not lead to shear-thinning. Additives may be used to confer resistance to oxidation, high temperature, water, acid, etc. "Soap" here really is soap -- a fatty acid salt, and may be natural or synthetic. Detergent (the "sulfonate" in calcium sulfonate grease) is functionally just like soap, with one hydrophilic and one hydrophobic end (this is what gives them micellular structure), but is not derived from a fatty acid. a combination of different soaps or detergents may also be used. Clays ("bentonite grease") are also used because they have immense surface area and can take up quite a lot of fluid (oil, presumably).


Things I still don't understand. 1) Hygroscopicity. Soaps and detergents are amphoteric (they like water and oil, which is how they work), and clay surfaces are full of polar ends of molecules (which is why they're so good at taking up water, better at water than oil). How is water absorption not a problem? 2) The role of the metal in soaps and detergents. The metal seems to matter and it's not at all clear how or why.

easyupbug 

I live in an airpark and it would be hard to find a hanger without airframe grease in it. It is excellent stuff and interestingly what i have is a lithium complex, it is great for bearings, good corrosion protection, usually rated for something like -100ºF to +250ºF but most interesting is it is a lot cheaper than Park Polylube which I think is a little less than $10 for 4 oz and Airframe grease just over $20 last I new for a typical grease gun tube, which is 14 oz. We have a Shell distributor right here in the airpark so if I had a galley with a sliding door I would probably go ahead and use it.

gfk_velo

Well, water absorption is a problem with all lubricants and greases are no exception - however, in greases, the presence of the oil slows the process down - however, grease in a very wet environment will slowly break down in terms of the fact that it will slowly absorb water - once water content goes beyond about 0.5% w/w, it becomes problematic. As it is absorbed by the thickener water has less mobility and as such creates less problems than it does when present in oils. By selecting right additives and with particular types of thickeners (Calcium Sulphonate and Barium complex in particular) there is a sort of cushioning effect which helps maintain lubrication even if water is present.
The metal is part of the saponification process - that is to say, a metal soap is obtained in a chemical saponification process. A fatty acid reacts with a metal hydroxide (a lye, for example Lithium); In this reaction process, the metal soap (thickener) and water are produced. So in order to make a metal soap grease, we need a fatty acid and a metal hydroxide (in an aqueous solution). There's a pretty good article cited below:
https://www.machinerylubrication.com.../grease-basics

FBOATSB

Interesting link. I know the bare basics of different grease/oil formulations, having done a lot of work in the places that make the stuff. I don't too pay much attention to the marketing waffle but notice the use of the term "MIL SPEC" to make us believe some sort of special mojo is in their grease. For instance, MIL-G-3545 is just a cross reference to 5 or maybe more high temp "aviation" greases. Important for aviation maybe, but my cheap tub of axle grease from the local hardware is fine for bikes IMO.

drlogik 

I can't recall if I posted on this thread or not. I apologize ahead of time if it's repetitive.

I still have two tubs of Campy grease from my days in the bikes shops back in the early 1980's. I don't use it anymore though, more out of nostalgia than anything else.

Technology has dramatically improved in lubricants over the past 40 years and grease is no exception. There are many great greases that work as well or better than Campy grease. Among them are Park, Phil's, Finish Line Teflon, Motorex, Penn and a few others. And yes, marine grease and regular bearing grease from the auto parts store work just fine too.

It's all personal preference. Me? I have a thing for Finish Line Teflon and Motorex 2000. They have served me well for a few years now and frankly, work better than the old Campy grease in my opinion. Believe me when I say this, it was hard, REALLY HARD to load my mid-1980's Pinarello Montello's all Campy bike parts with Motorex 2000. After a couple of years I pulled the hubs and they still looked "clean". The old Campy grease didn't do that and neither did the Finish Line.

A huge tub of Motorex 2000 will run around $30 bucks and last you the rest of your life and the lives of your next two generations of family members.

Or, go down to the auto parts store and buy a $10 dollar 1lb tub of bearing grease.

Of note, and also my opinion, the selection of grease isn't as important as how it is applied. Too much grease and it doesn't do its job well (no matter what grease is used) and can hinder the rolling resistance of the bearings. Too little and you may not get the lubrication you need and prematurely wear out the bearings. Apply just enough to hold the balls in the races and then fill in some of the gaps but don't "pack" it in. You should be able to twist the axle freely with your fingers once re-assembled. If the axle feels sluggish or has resistance to turning, you may have too much grease in the bearing.

sincos

Not to beat a dead horse or anything, but this uses the metal strictly for charge balance. That is, the organic part being the same, a barium soap would be no different (except maybe in weight) from a magnesium or calcium soap, and a lithium no different from a sodium or ammonium soap. But (and this is to be fair never stated outright) the literature -- or at least the brochures -- imply that the properties of the metal itself are important.
Interesting about the water absorption, thanks.

grizzly59

Mobilgrease 28 for my bikes. Good enough for Mach 3.3, good enough for me (Mach 0.0260665).

Camilo

In reading this thread, my conclusion is that it's better to use grease when and where it's needed than to not?

buddiiee 

Just to ensure everyone knows, that NB52 is NOT the same grease as Campy had in those tubs in the 80's. (unless I somehow got a jacked up tube of nb52) I used that crap on EVERYthing when I was a kid, I know it intimately, and would be able to spot it a MILE AWAY. This Kluber stuff I have here in this little tube is WAYYYYYY thinner, and way lighter in color than Campy grease was. Also, this Kluber stuff has a liquid component to it, or it's just separated, (something ive NEVER seen a tub of campy grease do) All I know is, this Kluber grease is so thin, I would never use it on anything. It just doesn't possess the same staying power as say campy or bullshot or the typical automotive greases do. It's runny and doesn't really stay put long. Like I said before, I just rebuilt a set of mint campy record hubs I had left over from the 80's and believe it or not they were just as silky smooth the day I got them. They rolled like a pair of well broken in sealed Phil Wood hubs do. I repacked them because I knew the age of the lubricant and it was the reason I sought a replacement to the famed Campy stuff. That search lead me to Kluber and I was sorely disappointed and ended up using Phil Wood grease.



Usually, and that's a big usually, when you use a thick grease, it makes the hubs (or any assy) quieter, but you get higher friction/more rolling resistance (the wheels spin a fewer amount of seconds when you spin and time them) than you do when you use a lighter grease. The lighter grease will allow them to spin longer but they will be a tad louder. (yes I can hear these things) I can also somewhat feel it when I spin them in my hands. Campagnolo grease was the only grease that defied this. When I repacked anything with Campy, it was not only dead silent, but rolled like I had used a light machine oil in it instead of grease. When I repacked these hubs with automotive grease or Phill Wood, I could never get back that smoothness or quietness that they had with the orignal Campy grease inside them. They roll really nice now, but I can hear them and feel them, and no, I'm not loyal to Campy. I love their stuff, but if something came across that worked better, I'd use it. (lubricant wise) so I'm not a 'fan boy' if you will.

Here are some comparative pictures. This stuff I have is NOWHERE NEAR my Campy grease I had in the 80's.

See how thin and white it is? You can see how thin it is by looking at how the black of the bottle shows through the thin layer on the mouth of the tube.

See the oil that came out before the grease? Note color.

THIS is the exact crap I used in the 80's (and some of the 90s) It's thicker and darker, & made hubs SILKY smooth AND quiet.

Racing Dan

I believe greases have gotten much better over the years (decades) and I have no reservations using what ever generic grease is at hand. I have done so, without issues, for years maintaining parents bikes. However, being a bike nerd, I did some investigation and came up with Motorex 2000 as a current favourite. Its soft and sticky and has a base oil viscosity suitable for low speed bearings, like in a bicycle. Incidentally its -very- similar to Shimano Premium grease. Id just get that, one or the other. Hunting for 40 years old unicorn grease is nostalgia, in my opinion.

LV2TNDM

Used to ride with a guy so fanatic and worried about his crank tapers failing, he used acetone to ensure EVERY LAST MOLECULE of oil or grease was removed. Boy his bike creaked like hell!
Been greasing tapers for 30 (nope, 40!) years. Only "crank" failure I've had was a Suntour BB spindle* failing on a Porcupine Rim drop off. Ah, the joys of riding Moab rigid back in the day!

*And yes, they were known for failing. But I was still very proud of myself.

PS The thread taper debate was FIRMLY ended by the west-coast version of Sheldon Brown, Mr. Jobst Brandt:
https://www.sheldonbrown.com/brandt/...ng-cranks.html

PPS Thanks for a GREAT thread! I LOL'd several times. Never realized Campignalio could be spelled so many varied ways!!!

PPPS Oh and as far as grease goes, using Mobil 1 red synthetic now. Still have a little stash of BullShot grease that I'm prolonging the life of. The only compelling specific grease argument I've seen involves S&S couplers and using their specified fluoro grease (https://www.sandsmachine.com/ac_greas.htm). It passed a galling test with impressive results. I figure on a tandem, using S&S's recommended grease is probably worth the cost. My stoker's life is, for sure. I think she'd appreciate the sentiment

LV2TNDM

That's actually a good point, analogous to motor oil perhaps? I understand motor oils are far better than they were (YT Engineering Explained is a good source). I just switched to synthetic motor oil and look forward to the 10k mile interval. Funny because after a trip to Utah last week, I've already put 5k on the van in a short amount of time. 200k and counting!

smd4

Used Phil Wood grease until last year, when I rebuilt my Dura Ace 7400 pedals from 1984--and saw that the Shimano premium grease in those pedals was as translucent a green and as viscous as the day it was installed.

beng1

Probably the best statement in the whole thread. Bicycle bearings are so lightly loaded that they would probably work fine forever with any sort of lube there is, bacon grease, used engine oil, or anything else that would just keep them from oxidizing from the moisture in the air. Any real cyclist will be on top of their bike's bearings frequently, so that is another reason it just does not matter. And if someone never cares enough to inspect or adjust their bikes bearings, it absolutely does not matter.

gfk_velo

Uhhh, no, not quite. Different metals do confer markedly different characteristics to the soap. They also potentially have different interactions with the other elements in the bearing.Check the differences in the characteritics of, say, a copper grease vs a molybdonum grease, or molybdonum vs Lithium.

I know it's deeply fashionable to disbelieve everything that one reads about a product, especially when it's written by the makers of the product - that was kind of where I came in. However, as part of my own self-imposed CPD requirement, last month I spent some time at a school of engineering near us - BAe Systems (who presumably know something about this stuff) and I talked with a couple of their guys. Long and the short - yep, you can put Filtrate grease into some of their high speed, high load bearings - but don't expect it to still be there doing it's job after they've been run up for more than a few seconds ... whereas high temp, high shear resistance formulations using barium, for example will do the job. Part of that is the metal base used. I asked that question very specifically.

Camilo

I hope OP is happy now.