Grease: Lets get technical

[LD1]

Long story short, I have been analyzing all the various types of grease we use at work. And there is SOOOO much technical information when it comes down to it. But basically, a greases job is to lubricate. So I am trying to decipher what makes one grease better than another.

So bear with me here.

I have been trying to compare all of these brands, but I have to narrow it down to the most IMPORTANT specs. So for now, I am going with the ASTM 2266 and ASTM 2596 specs. Feel free to google them. But it is basically a 4-ball wear test. Important specs are scar depth, and the weld load. Lower is better on scar depth and higher is better for weld load. There are some other important #.

But the greases we use at work are as follows

grease.............................scar depth...........weld load
mobil SHC460....................(.5mm)..................250kg
Mobil XHP222.....................(.5mm).................315kg
Tribolube -9......................(.86mm)................315kg
Tribolube 3.......................(1.1mm)................315kg
FUCHS Renolit Moreplex.......(.35mm)................400kg
mobil shc32.......................(.7mm)..................200+kg
Mobil EP1..........................(.4mm)..................250kg
Mobil EP2..........................(.4mm)...................250kg

Those are just some that we use at work. And I know there is more to it than just those two specs, but IMO, those are the EP tests that determine how well the grease does its job (lubrication). So WHY does the EXPENSIVE synthetic SHC460 not do any better than the EP1 and EP2???

And here are just a few more greases that we all may have used

XHP322...........................(.65)......................250kg
Sta-plex EP Red ($4/tube)...(.4mm)..................500+kg

So why is the cheap Sta-plex look so much better on paper. Even on some of the other tests, like a 77 LWI, which is higher than any of the above. Or the 500 degree drop. Or the 60lb timken test???

Sorry for the long winded post. Just lookig for some feedback from some of you that may be more knowledgable about grease than me. I know this is just a snapshot overview, so I challenge you guys that read this to look up the specs on the grease that you use and post here.

But I have to ask, What makes some of the more popular greases like the SHC460, xhp222, xhp322, etc worth 3-4x's as much as the $4/tube sta-plex that appears (on paper) to outperform almost all the other greases I looked up??????:confused2:

 

[MHarryE]

I may not have much help for your question but I can add some information based on my engineering experience.

The Fluids Group at the company where I worked provided our answers so I am limited to issues where I had a problem, and I didn't have many grease problems. I did find out that the 4 ball wear test was a standard created ages ago that can be misleading. I once had a very high temperature lube problem that a supplier came by with this super grease that did fantastic in the 4-ball wear test. He assured me it would cure my problem. I sent a few sample tube to our Fluids Group where they found the grease did indeed do well in the standard test, but failed miserably in some of our proprietary in-house tests. We ended up redesigning the bearing application so we could pressure lube with oil that would carry the heat away.

I had a lot more experience with gearboxes - straight cut gears, roller bearings and tapered roller bearings, oil lubrication. In our testing the Mobil SHC full synthetics were superior. I have inspected dozens, possibly hundreds, of disassembled gearboxes and found I could easily identify those where a customer had substituted a SAE50 (for example) transmission oil in place of our standard SHC630 because of pitting and other problems. SHC630, however, is unacceptable in a gear application where EP oil is required. Hypoid gears like the input of some of our differentials were definitely out of bounds. In those applications we used a gear oil with EP additives such as 80W-90 or 75W-90 synthetic. I ran Mobil 75W-90 synthetic gear lube in the front axle of the Kubota I just traded because of my experience. The axle does not exchange fluid with the rest of the tractor and is therefore not cooled. Some of my worst experinces at work came from gearboxes that generate a lot of heat when operating at high speed with no external cooling. The oil breaks down. SHC oils give, in my experience, at least 25ｰF additional capability.

So as I remember the 4 ball wear test, a lubricant with EP additives may prove superior just because of that capability.

My Caterpillar mini-excavator specifies NGLI Grade 2 but beyond that they say they recommend the lube have at least 5% molybedenum. I use the only grease at my local discount store that has any moly - 3% - and also meets NLGI Grade 2. That discount store is only 3 miles from my Cat dealer - right now I can't tell you why I don't go the extra few miles to get the Cat stuff. I had my Kubota tractor for several more years than the mini-excavator. I always used Mobil 1 Synthetic Grease in the loader linkage, identical application as the bucket linkage on my mini-excavator. I can tell from experience the grease including molybenum sticks in the joints a lot better. The only advantage I see to the Mobil synthetic is that it will hold up better under extended high speed operation. Sounds great for trailer wheel bearings but I not applicable to the pins on my loader or stick on my excavator. So with my new L5740 the Mobil 1 is going by the wayside and I'll be using a grease with molybdenum additive.

 

[RickB]

In 99% of the uses commonly discussed on TBN, any grease is better than no grease, and more often is better than not very. IMHO grease is a topic overdiscussed and underapplied.

 

[Transit]

Which grease to use depends on the application, remember that tractors are lubed every day, they run on grease.
A brand name EP molly grease should be more than up to the task.

LD1, from your list, which contain molly?

 

[LD1]

I believe the only ones on the list with moly are the triboube -9 and mobil xhp322.

But I still cant figure out why they dont appeap to perform as well "on paper" when I thought the moly was supposed to make it have better EP characteristics:confused2:

 

[MHarryE]

We really found moly to work great on splines with a lot of vibration. On one engine to hydrostatic pump application we could knock the splines out in 200 - 300 hours. Fluids group suggested a high moly lube with o-rings on each side to help keep it in place. After that never tore one down that showed any significant wear. Don't know about it being good for EP - out of my ballywick. That's the advantage of working for a company that can have specialists on everything. The help is there for you when you need it, but you really get to know only about the stuff where you have problems.

 

[retiredmgn]

Well this is interesting. I wasn't aware of such complexities of lubrication. An area to educate.
Gramp would always say, "Everything goes better with a little grease". Hard to argue with that. He worked on Model T's in Aroostook County Maine. Choices of lube were apparently a tad more limited than what you guys are discussing.
I'm all ears...Fill me in.

 

[LD1]

Well this is interesting. I wasn't aware of such complexities of lubrication. An area to educate.
Gramp would always say, "Everything goes better with a little grease". Hard to argue with that. He worked on Model T's in Aroostook County Maine. Choices of lube were apparently a tad more limited than what you guys are discussing.
I'm all ears...Fill me in.

Thats kinda the point of this thread. Because I dont know as much as I would like to about grease.

I am hoping that people on this forum can educate me as well on the more technical side of things. AND why one grease is better than others for different applications. And NOT just the old "I use xx brand and nothing but" type claimes. I am a scientific guy and I like hard numbers and proof. So if you believe one grease to be better than another, show some #'s to prove it.

Like I said, I dont know as much as I'd like, but it seems that every grease I have looked at has all the ratings that ASTM sets forth. And some greases clearly do better than others. And there are far more tests and ratings that I didnt mention above, like LWI, Timken OK load, Drop point, penetration test, etc.

 

[LD1]

Let me try posing this question/goal of this thread a little differently.

Assume cost is no object. Because the cost of failure is many times higher than the cost of even the most expensive grease,

Of the above listed greases, which would you choose and why.

It is ok to seperate into two categories of choices, 1. Best for high speed bearings. like mower deck bearings. 2. Best for Extreme pressure pins and bushings (like loader and backhoe pivots).

The following is links to all of the above 10 greases and their specs. Maybe some of you who understand what the different ratings mean in "real world" terms can better enlighten us that are in the dark:thumbsup:

Mobil SHC Grease 460 WT

Mobiltemp SHC Series

Mobilux EP 1 | The Lubricant Store

Mobilgrease XHP Mine Series

Mobilgrease XHP 220 Series

http://www.aerospacelubricants.com/files/sheets/t-9tds.pdf

http://www.aerospacelubricants.com/files/sheets/t-9tds.pdf

SL3191 -- Sta-Plex™ Extreme Pressure Premium Red Grease, 14 Wt Oz

http://portal.fuchs.com.au/images/datasheets/Renolit Moreplex 2HV.pdf

 

[RickB]

Let me try posing this question/goal of this thread a little differently.

Assume cost is no object. Because the cost of failure is many times higher than the cost of even the most expensive grease,

Let me answer another way. I would use any general purpose grease that was commonly available at a location where I happen to shop for other parts and supplies.

I know you don't like my answers, but like I said before, grease is overthought and underapplied. Specification matching and ingredient shopping for the perfect grease will not materially improve the service life of the average CUT or attachment beyond what any old grease will provide when applied at the indicated intervals.