Yesterday, I did my homework. I read about this till blood was squirting out of my eyes. This is certainly not my area of expertise. I am not hanging my hat on what is correct based on the TM, simply because we have lubricants available to us now that simply did not exist back then.
Of course, an important thing to keep in mind when selecting the "correct" lubricant is that this is not a high-speed gearbox and I can see how some fellows erroneously conclude that chassis grease might work since this is a low speed application. Among the many reasons why chassis grease does NOT work is that a "correct" steering gearbox lubricant must be able to efficiently follow the bits and pieces as they move around in the gearbox, leaving no voids. Thus, we are looking for a lubricant that is more oil-like than grease-like....something that is a bit like honey.
As has already been discussed at great length, grease will simply push out and not return to the areas requiring lubrication.) My advice to anyone who has introduced grease into their steering gearbox is that they take the time to remove it.
Also, the "correct" lubricant would benefit from having the same qualities over a broad range of temperatures. This has been achieved with many modern lubricants. So, arguably, with the "correct" modern lube, the need for changing gearbox lubricants for seasonal purposes can be eliminated from your bi-annual maintenance list. Of course another parameter is that the "correct" lubricant also be formulated in such a way that it not have an adverse effect upon the yellow metals present in the gearbox. These things were on my mind.
I started with the following. Found it interesting but it can be a bit misleading especially if you assume viscosity is all there is to it -
https://www.glennbennettcorp.com/hubfs/ ... erence.pdf
This next, very scholarly piece helped a lot, particularly this simple phrase which I used as a guide "Generally speaking, a high-quality worm drive lubricant will have low friction, high oxidation resistance, good anti-wear protection and high viscosity index." I don't pretend to understand all of the article but I think I got what I needed out of it -
http://www.machinerylubrication.com/Rea ... worm-gears
I also revisited the topic on the CJ2A forum where a lot of opinions were shared. -
Then I went to youtube and saw HOW the tests (applicable to the product I'm presently considering) were performed. They also show what the resulting damages are. The first two tests take place at very high speeds -
https://www.youtube.com/watch?v=kEv1hSJTQTM
https://www.youtube.com/watch?v=eLcy5YHDNbo
https://www.youtube.com/watch?v=uniCjnOg7mE
And, through the power of the internet, I finally came upon this synthetic (!!!) the qualities of which I'm presently discussing with my buddy, who is an honest to God chemist and who worked at places like Red River refurbishing military stuff. The information provided on the technical data sheet of these products is really important and if you are serious about finding out about your lubricant, you absolutely must look at that.
https://www.amazon.com/gp/product/B00LX ... UTF8&psc=1
Technical Data Sheet. What I'd like the reader to take away from this are the PROPERTIES of the product. Point of interest, in the product I'm presently examining, ISO 460 has a slightly higher viscosity than ISO 680, yet 680 is a bit better performer in the scar test (so, surprise surprise! - viscosity really ISN'T all there is to it, right?)
http://www.super-lube.com/files/pdfs/Te ... ar_Oil.pdf
In my physical searching, I learned that what we generally would require for steering gearbox lube is really not to be found on the shelves of auto parts stores in any amount, chiefly because its popular use has been lost to antiquity. This doesn't mean it's not out there. It simply means that we may be looking in the wrong place, eh?
I learned that the term "Food Grade" is not to be automatically dismissed as something that is necessarily WRONG for those of us in the automotive world. In fact, the use of additives like sulfur and phosphorous is a huge no-no when it comes to the formulation of food grade lubricants (the FDA obviously frowns upon it), SO, finding a food-grade lubricant that we can use (one that is H1-rated) is VERY good indeed!
The key point of the following link was the general discussion of the H1 rating (An H1 rating has been achieved by the synthetic lubricant I'm considering) -
http://www.machinerylubrication.com/Rea ... lubricants
One of my main parameters is that the lube do its job (beyond the obvious lubrication performance issues) - that it will not be prone to leaking, that it will not be damaging yellow metals, that it will not be degrading over time.
Another thing high on my list is that the lube be readily available, not only for myself, but also for the NEXT guy who owns this truck. Procuring some mysterious lube from someplace that is never to be found again really doesn't help that guy.
And so, in the time it took me to write this, the decision has finally been made. Super Lube 54632 Synthetic Gear Oil ISO 680, 1 quart Bottle, Translucent, is the product I selected for use in my steering gearbox. It will be several days before it arrives but when it does, I'll share some photos.
Cheers,
TJ