Cross-posted from another list. The example given is for a Toyota Land
Cruiser but I thought the information was useful regardless:

>Date: Mon, 29 Apr 1996 01:32:06 -0800
>From: jbarron@uvic.ca (John Barron)
>To: offroad@ai.gtri.gatech.edu, Rocky Baker <bakerr@ucs.orst.edu>
>Subject: Grease--what it is, types to use in LCs
>
>>Subject: Grease types (chassis, u-joint, blue vs black)
>,
>>Would someone know the difference between molybedenum disulfide lithium
>>base chassis grease (NLGI no. 2) and lithium base wheel bearing grease
>>(NLGI no. 2)?
>>The first is recomended for the steering knuckles on my 85 FJ60 and the
>>second is for the U-joints.
>>Second question is:  Does Toyota use a blue colored grease for any
>>reason?  The grease in the steering knockles looks blue but the grease of
>>the recomended type at the auto store is black.  Any problem with mixing
>>these?  Do I need to buy Toyota grease for this rig?
>
>>Thanks,
>>Rocky
>
>First of all we need to know what grease is:
>        Grease is a lubricant. It is produced by combining lubricating oil,
>additives (eg Molybdenum Disulfide), and a soap.
>
>        The lubricant in most greases is a (petroleum based) mineral oil,
>although some greases use synthetic lubricants. The soap emulsifies the
>lubricating portion and thickens it. The type of soap used in making the
>grease is one way in which greases are classified. For example, a lithium
>soap is used in a "lithium grease". The actual lithium soap is properly
>known as 12-Hydroxystearate, other greases will use other types of soaps,
>for example, Aluminum.
>
>        Greases made with different types of soaps will usually be
>incompatible and cause the grease to liquify or fail in some other way.
>Liquified grease will not adhere to the intended surfaces and the result
>will be that the parts will not be sufficiently lubricated and fail as a
>result. Other grease failure problems can be related to contamination
>(water, dirt, oil etc...), infrequent changes, overheating, mechanical
>shear and other forces.
>
>        There are many additives that can be put into grease to give each
>type of grease unique properties. This also make some greases much more
>suited certain types of jobs than others. Some of these additives may be
>colourants, corrosion inhibiters, helping the grease resist shear forces,
>make it more tenaceous, help it resist water contamination etc...etc...
>
>        Molybdenum Disulfide (aka "Moly") helps the grease film carry a
>load and is most often a grey to grey-black in colour. Other greases, such
>as wheel bearing grease, may be green, blue, yellow, red, white, or another
>colour depending on the colour of the lubricating portion or the colourant
>used. Colours can help to identify what type of grease has been used but
>are widely variable and, as such, are not a reliable indicator.
>
>        A few more grease notes: NLGI stands for the National Lubricating
>Grease Institute, they are a body that sets standards for greases. The
>viscosity of grease, as labeled by NLGI, ranges from No. 000 (runny) to No.
>6 (very thick, almost solid). The viscosity is quite important to the
>application so use the right one.
>
>        Anyways to get back to the question at hand... No not all greases
>are compatible. If you don't know what type is there, then replace it with
>the correct (and known) type of grease as specified by your owners/service
>manual. Make sure you use the right viscosity. The grease may say it's a
>Moly grease but give no viscosity--find out what it is before using it.
>Moly adds shear resistance in low speed applications (speed of moving parts
>being relative to each other), use non-moly grease in wheel bearings as the
>relative speeds of the parts is high. The colour is not always relevant,
>the fact that there is blue grease in your knuckles may mean that there is
>a non-moly grease in there (as I personally have never seen Moly grease in
>any other colour except grey-black). The colour of Moly grease is, I
>believe, related to the Moly itself--changing the blue stuff for the
>correct grease would be a good move when you can find the time to do it.
>Also, try checking with the shop that last did the service on your LC to
>find out what type of grease was used.
>
>        Toyota Specs:
>
>- -Propeller Shafts (drive shafts/U-joints): Lithium base NLGI No.2
>
>- -Double Cardan Joints (drive shaft "CV" joints): Molybdenum Disulfide
>Lithium base NLGI No.2
>
>- --Wheel Bearings: Lithium base multipurpose NLGI No.2
>
>- -Steering Link ends (tie rod ends): Molybdenum Disulfide Lithium base
>NLGI No. 2
>
>- -Steering Knuckle and Front Axle Shaft: Molybdenum Disulfide Lithium base
>NLGI No.2
>
>Need more info?? write me at my email address directly.
>
>jbarron@uvic.ca
>81 BJ 42 (with broken rear springs)
>80 BJ 40 (with factory rust option)
>
>------------------------------

--Ken
  68 Westy, 71 Bus