Unless MB has changed their policy and not told me, Kestas is right on at least one matter. MB publishes a Recommended Fuels And Lubricants List. The products listed are products that MFGs have submitted to MB for testing at their expense. If the product passes MBs testing, it is listed. That doesn't mean that a product made to industry standards isn't just as good, because it isn't listed. It is pretty much the same as Underwriter Laboratories. Most people take the little UL sticker to mean UL approved. The UL sticker means it has been tested by UL, passed the bare minimum standards, and is now UL listed.

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Auto Zentral Ltd.

You might be suprised....

But from what I've seen more and more- dealerships take oil fluid samples on failed parts. That way they can send it to the lab and when it comes back that you have your synthetic oil in the diff..... it will be your dime, not mb's.

I follow MB's recommendations. They seem to update the lubrication sheets with some regularity. That to me, says they are on top of it. API specs don't always align with manufactures. I remember reading in 2000 a survey that showed 90% of the oils tested didn't meet API spec on the bottle!!!

As for the grease- incompatibility *is* a problem at times. Heck, I can remember an alaska airlines plane that went down due to the wrong grease was attacking the worm-gear.

The best argument for using the factory grease- is it's really fantastic grease. It is made by shell I believe- it's the same thing that the F-18 fighters have in their wheel brgs (so I've been told). You'd have to go through the mil-specs.

Please tell us how brgs have NOT changed in 60 years... is it not now common to use 1050 steel instead of the 52100???

Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E

52100 steel has been around since before WWII. There have been some subgrades developed over the years for specialty applications, but the basic chemistry of the workhorse 52100 hasn't changed over the decades. The only thing that has changed over the years is the cleanliness of this steel and the precision used to machine the parts.

Yes, 1050 steel is sometimes used in bearing applications. It's an induction-hardening grade of steel, but that doesn't make it a bearing steel same as we think of 52100. We often use it in hubs where the race is machined right into the forging. There are many other grades of steel used in bearings. I've even seen ceramic rollers. But for this discussion nearly all automotive seperable races that are through-hardened are made of 52100 steel. Nobody's been able to come up with anything better.

When a lubed part fails and is sent to the dealership under warranty, it is often because of lack of maintenance, which is often obvious to the mechanic. The lab analysis simply quantifies and documents this fact. I'm sure most of us have read the horror stories of cars that come into the dealer for the 30K maintenance, and the mechanic finds the oil has never been changed! This is usually the point where a dealer will ask for a lube analysis. It's rare that a vehicle that has seen timely maintenance would experience a lube failure.

I highly doubt that synthetic lube in a differential would result in degradation of the unit. For diff lube, there is always some "synthetic" in the lube to carry the additives. It's really a question of how much of it is synthetic.

The believe the sequence of events, where somebody maintains their differential lube using a proper grade of synthetic, then has a failure under warranty, then has the mechanic send a UOA on the lube, then the lab discovers it is synthetic, then denied warranty because it is synthetic, is far and remote. The average person doesn't even think about their diff lube much less do something about it.

I'd be interested to see the product data sheet on MB grease. I'm sure it's fantastic grease. There are many others that are good and fit the application. Heck, I believe ExxonMobil has the best wheel bearing grease, better than their popular Mobil synthetic. It's called Infinitec 152. It's specially developed for automotive wheel bearing application. I have a 5-gal pail of it. It is not available over the counter. I doubt MB manufactures their own grease. Most companies - ours included - buy existing formulations and slap their company's name on it (and tack on a premium). There are only five manufacturing facilities in the US that make grease.

The reason the Alaskan Airlines plane went down was that the airlines extended the maintenance interval for the worm screw, not from wrong choice of lube or lube attacking the mechanism. The lube basically wore out and inspection wasn't often enough for that application.

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95 E320 Cabriolet, 159K

You really need to go back to the FAA report..

Yes the gear was worn, but *the wrong lubrication was a contributing part*.

I appreciate you know your brgs. Compatiblity is a problem on greases. Have you read your manual? ? Have you pulled any of the current MIL specs for grease??

I've seen big disputes on engine failures where the factory dennied the warrentee claim because they were using a non-approved oil. The lawsuit side of it, was the dealer had done all the oil changes.... But, it real just comes down to money-not logic.

How many diff failures have you seen in mercedes which have regular fluid? I've seen them run low on fluid and failed-but no failures related to the quality of the fluid. I replace my diff fluid with a 85W90 which is approved and don't think twice about it. If you want to throw an extra couple of bucks on syn diff oil- go do it. Nobody is say for you NOT to. We're just informing you of the rquirements.

And since you didn't seem to read this paragraph the last time I posted it by your comments.. here it is again

"The best argument for using the factory grease- is it's really fantastic grease. It is made by shell I believe- it's the same thing that the F-18 fighters have in their wheel brgs (so I've been told). You'd have to go through the mil-specs.
"
What is the mil- spec or NATIONAL supply code on the grease you are using?

Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E

I read your paragraph. I simply chose to ignore it. Though it sounds impressive, because this grease is used on fighter aircraft does not mean that those wheel bearings are very demanding on the grease. I don't know. Sometimes very mundane applications can be the most demanding on grease.

What kind of compatability are you talking about?... you have to be specific. If you remember, I was the one who provided the link for the compatability chart, and I'm a big proponent of thoroughly cleaning a bearing before regreasing.

OEM in Detroit is going toward synthetic differential fluid for factory fill. The reason is that synthetic allows them to up their CAFE an incremental amount. They wouldn't be spending the extra money for synthetic fill if it didn't pay off. This, and the fact that CAFE requires the cars be tested with factory fill. I've never been a big proponent of synthetic lubes except when it comes to diff fluid. The extra incremental MPG you get from synthetic diff fluid pays for the premium you have to pay on the liter and a half lube charge.

I didn't read the FAA report. I read the NTSB report. You quoted, "the wrong lubrication was a contributing part". If you mince words - and these reports are carefully written - this can also mean the wrong practise was used. Otherwise they should have said "the wrong lubricant was a contributing part". Perhaps the rest of the report can clarify this issue.

We use many different lubes, depending on the application and what the customer is willing to pay. I'd be at a loss to name them all. Very often we're at odds with OEM manufacturers because they don't want to pay the premium for better grease in the bearings we make for their vehicles, despite the lube problems we see on their product returned to our lab.

We don't work with MIL specs. It sounds like you do.

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95 E320 Cabriolet, 159K

Yea,

I have access to the mil specs. I try to stay away from the lubrication stuff, as it is set in stone. The two tyes we commonly use are NOT compatible and everything has a shelf life. I think expensive brg assys get sent back to the manufacture and re-worked after the shelf-life with new grease, seals after cleaning and inspection. But, that's not my field. I'll stick with structures and dynamics plus lots of laboratory composites.

That's curriously, trying to save cost with subsituting. We are more a low-volume and anything other than standard practices costs us $$$ from the suppliers.

On, this wheel brg note. Are you assuming MB engineering is overkilling and using a high-quality grease accross the product line ??? On this note, I always liked MB in that they actually follow the manufactures bearing preload/clearance instructions.

Do you use a dial indicator as the maual and set the clearance to 0.01-0.02mm?

Just currious!!

Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E

I'm not familiar with MB wheel bearing grease. I just know it's green. Like I suggested earlier, I wouldn't be surprised if it's just the same formulation (and perhaps custom-dyed) grease that's commonly used elsewhere.

Yes, I use a dial gauge for my wheel bearings. I do this for two reasons - one is I know how critically important proper axial play is for the life of an automotive wheel bearing, and two, I have access to a gauge set at work. When giving advice on this board, I'll tell people to use a dial gauge, but then I'll also instruct them how to approximate a good setting without one because the reality is that not everyone wants to shell out the money for a dial gauge set, yet they will go ahead and service their bearings. And a propoerly executed backyard approximation on the axial play will do just fine in most cases.

There's been a lot of emphasis in this discussion on the grease used in bearings. From my end, forensically looking at failed bearings, I find that seals play an even bigger role when it comes to lube problems. A seal failure will allow water and contaminants to come in, and grease to purge out.

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95 E320 Cabriolet, 159K

I had always hear that the grease quantity was critical.

If you get too much, the hydrodyamic fluid movement of the grease is impinged, and the brg runs hotter.


Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E

Not critical so much as kept in reasonable control. The bearing should be filled completely with grease, but the free space should be only partly filled. In vibrating applications, such as wheel hubs, grease should fill no more than 60% of the housing.

You may be thinking of grease flow within a bearing. I believe this is a consideration when designing a greased bearing. I've seen some bearings after life test where there was black, used-up grease next to fresh, as-new grease, indicating poor flow of the grease within the bearing. I've never seen perfect flow where all the grease is used, but the flow should be maximized as much as possible to extend useful grease life. Inner rotating designs are always better than outer rotating designs for this and other reasons.

Too much grease can result in purge from the bearing. Too little grease will result in reduced useful life of the grease. Therein lies the balance. I too have heard about overheating being a problem. Most service manuals show the proper way to regrease a bearing. Apparently, MB's approach is to specify the amount of grease, let the mechanic pack it in the bearing, and distribute the rest within the housing. Either way should work fine. Some people get too happy with the grease and pack as much as they can in the empty spaces, which is not good.

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95 E320 Cabriolet, 159K

WOW This is turning into an oil thread, only thicker. Perhaps some of this material could be incorporated into a book entitled EVERTHING YOU NEVER WANTED TO KNOW ABOUT GREASE. I enjoy reading on many subjects like the Civil War, The plague, The Knights Templar, and such, but I haven't read much on grease lately.

As to bearing clearance, I don't know of any professional mechanics who use a dial indicator. It's all done by feel. I once asked a German mechanic how tight to tighten a bolt and he said, "tight is tight". It took a long time for me to grasp that concept.

I still say it doesn't matter who's grease you use as long as it matches the application. The only vehicle that comes to mind where I would have to critically chek specs of a product belongs to a guy who lives 20 mile down the road from me. His car didn't come with an owners manual. He built the car himself. His name is Craig Breedlove. When you are driving a car close to the speed of sound, you want everything to work perfectly.

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Auto Zentral Ltd.

So, one question:
Does all this mean you should Not just let the grease monkey at Jiffy Lube shoot something back in the axle, as was suggested?

If the grease monkey at Goofy Lube had received the extensive training required to recognize grease fittings, I'm sure the grease would be compatable. I don't think they spend much time on the L part of LOF. They concentrate more on selling you an air filter or new wiper blades.

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Auto Zentral Ltd.