When should you use grease with moly?

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I use moly grease in everything. I have not had a u- joint failure since. Some people say that moly lube I'll allow a bearing to skid instead of roll but my Ford came from the factory with moly grease in the hub's.

I replaced the 27 yr old u-joints in my truck with grease ables and so far over 40k no issues. Jeep is about 70k on moly grease
 
Moly is considered a solid lubricant that is well suited for sliding forces like a driveshaft spline into a transmission.

Theoretically, though, moly does not belong in roller bearings where it will potentially cause the rollers to flat spot from not spinning.

I tend to stick with non moly lubes in my grease gun since there are more things that will accept traditional grease.
 
No flat spots yet. Grease, rinse (in mud), repeat. That procedure served me well so far.
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Moly greases are usually called for in applications that involve a lot of sliding or linear wear patterns, rather than revolving or high speed applications.

In reality, Moly can be used in any application, so long as the grease contains 5% or less moly. One of my favorites, Valvoline synpower; contains 3% moly in a lithium complex base. It is rated for disc brake wheel bearings and I use it in everything! Bearings, tie rod ends, ball joints, u-joints, drive shafts splines and grease zerks galore! Never a problem with anything, ever!
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I was always wondering why is moly lithium grease deprecated to be used in bronze bushings ( in plain bearings)???
 
Originally Posted By: AMC
Moly greases are usually called for in applications that involve a lot of sliding or linear wear patterns, rather than revolving or high speed applications.

In reality, Moly can be used in any application, so long as the grease contains 5% or less moly. One of my favorites, Valvoline synpower; contains 3% moly in a lithium complex base. It is rated for disc brake wheel bearings and I use it in everything! Bearings, tie rod ends, ball joints, u-joints, drive shafts splines and grease zerks galore! Never a problem with anything, ever!
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Originally Posted By: AMC
Moly greases are usually called for in applications that involve a lot of sliding or linear wear patterns, rather than revolving or high speed applications.

In reality, Moly can be used in any application, so long as the grease contains 5% or less moly. One of my favorites, Valvoline synpower; contains 3% moly in a lithium complex base. It is rated for disc brake wheel bearings and I use it in everything! Bearings, tie rod ends, ball joints, u-joints, drive shafts splines and grease zerks galore! Never a problem with anything, ever!
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Good information, thanks.

I'm taking it then that the Sta Lube grease I linked above is acceptable for U Joints.
 
The product info says u joints right on it, can't see why not.

I wish it said how much moly it contains but that is ok. The product info says it can be used in wheel bearing but it doesn't specifically say disc brake wheel bearings or have the gc-lb rating so I would use something else for high speed wheel bearings. Most other general purpose applications though, go for it.
 
Originally Posted By: Farmer
Don't use it in ujoints.

Wrong!

that's one of the best uses for moly

anything that "slides" or rotates you should use a moly fortified grease 5%

Pins,bushings,5th wheels, splines, low speed bearings, just to name a few.

that's our main grease we use.
 
Originally Posted By: Reddy45
Theoretically, though, moly does not belong in roller bearings where it will potentially cause the rollers to flat spot from not spinning.

This is the first I've heard of that. Is this published anywhere that is authoritative?
 
In a previous life I managed a construction company that had a small-ish commercial truck fleet. When I prohibited MoS2 grease from anything except sliding splines and ball joints, our u-joint and wheel bearing failures (which had been a problem) were completely eliminated.

This is a subject of polarized opinions, and I am not questioning in any way anyone who does not agree, but for just myself alone, no MoS2 in roller bearings -- especially needle bearings-- ever.
 
Originally Posted By: Sylvatica
no MoS2 in roller bearings -- especially needle bearings-- ever.


Yes, deficient thermal conductivity [in most designs] causes needles to flatten one by one, until it's too late. Spindle needle bearings in LandCruisers are prime example: some dealers cut corners on correct grease and use one universal kind, while that vehicle needs 3 different kinds for different units. Works fine for the first couple of hundred thousand miles on asphalt, fails miserably on off-road trails much, much quicker. I can imagine in commercial and industrial world this would be a major draw.
 
I'm not against moly fortified grease but none of my trucks ever had so much as a tie rod end go bad, certainly not a u-joint (using lithium complex GC-LB rated non moly grease).

Granted, I try to grease my trucks every 3k-5k miles and I'm in the otr business, not mining or construction. Still, some of my trucks have gone way over a million miles without a greased part going bad. I thought that was normal, though.

My new truck's owner's manual says not to use moly grease in the slack adjusters (brakes) because it will shorten adjuster life and could affect function.

Just sayin' moly grease isn't necessary for long lived parts in vehicles. I can't speak to any other machinery.
 
Moly is a solid lubricant that builds on itself. If your manufacturer advises a no-moly grease, follow the manufacturer.

Some solid lubrication additives don't build on themselves, but you pay for that. LE Almagard is an example.
 
From a Tundra thread, by a lubrication engineer:

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Moly additized greases are excellent lubricants,however, should only be used in limited applications as the moly can actually cause early failures in most uses. Never, ever use a moly additized grease in a wheel bearing or universal joint application. Moly additized greases are primarily indicated only where extreme pressure sliding action occurs. When Moly is used in non-friction bearings the moly causes accelerated surface degradation (frosted mug appearance) of the rolling surfaces and premature bearing/race failure. The moly is actually harder than the hardened bearing surface and does not crush when the bearing rolls over it. In universal joints, in addition to surface failure, the moly centrifuges to the extremes of the bearing, blocking oil flow, causing accelerated bearing end wear.
If a single grease is being considered a non-moly grease is the safest primary recommendation. The use of both moly/non-moly specific for sliding/bearings application is ideal.
I currently have 5 failed universal joints sitting on my lab table with very low time; all were regularly greased with a moly additized grease and each failed due to the use of the moly grease.
George Morrison
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I know what the manual says with respect to U-Joint grease. My statements are from a lube engineer's perspective (along with 6 inches of scar tissue on derrier from having used Moly in U-joints before this was known!). CV joints, however, are another story.
Purging the U-joint will work fine; it is continued use of the moly grease over time which causes the problems..
One can never go wrong using a high quality non-moly grease in every applilcation (except CV joints), however the same is not true of moly greases. There are so few real applications and need for moly additized greases and so many potential problems as a result, moly greases are like a curse for us lube engineers..
George Morrison, STLE CLS
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We should never, ever use a Moly additized grease for wheel bearings or any non-friction type bearing. Moly is superb for plain bearings (anything without ball or roller bearings) such as are used in back-hoes, bulldozers, etc. In these cases, severe impact loading can exceed the film strength of the base oil and the moly can act as a fail-safe lubricant and work superbly. However, in non-friction bearings we are relying on the oil film to do the lubrication. Grease is composed of 80 to 90% oil; we are lubricating with oil, just as tho you were oiling the bearing with an oil can. The remainder 10% is sponge which holds the oil in suspension for use when pressure calls for its need.
Color has no bearing on grease performance EXCEPT for one area: never use a black grease in a non friction bearing/wheel bearing/universal joint. Period.. Use yellow, purple, pink, red, whatever, just no moly. Moly will give a steel grey appearance to a grease. There are black greases which contain no moly and they are fine, of course.
George Morrison, STLE CLS
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YMMV, of course
 
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