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Do you have to use neatsfoot oil or castor oil to soak leather, or is there a common oil I would have in my garage?
Thanks

Gerry, I have always used just a light oil like Marvel Mystery Oil to soak leather seals. However, if you are doing the differential pinion I suggest upgrading to a buna lip seal via one of the two ways discussed here recently

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I already purchased the seals before the thread came out about the other options so I will try the NOS seals. I found some neatsfoot oil to use.
Thanks,
Gerry

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Thanks,

M-Thrax wrote: I know leather seals is taboo here but I had them on my 37's pinions.

I wouldn't say that leather seals are "taboo," exactly. They were original equipment and some "purist" restorers may prefer to use them simply for that reason. I will say, though, that if you have leather seals, sooner or later they will leak.

Lifer wrote:

M-Thrax wrote: I know leather seals is taboo here but I had them on my 37's pinions.

I wouldn't say that leather seals are "taboo," exactly. They were original equipment and some "purist" restorers may prefer to use them simply for that reason. I will say, though, that if you have leather seals, sooner or later they will leak.

You speak the truth, more likely the leaks will come sooner than later.

Like most other issues, in automotive technology things have come a long way since leather seals and straight 90 weight mineral oil were all that could be had; oil leaks were common and paid little to no attention. Current production seals are the only way to stop the leaks, and it isn't likely they will stop it unless you install a redi-sleeve to renew the yoke seal mating surface.

Give this fact some thought. Did you realize why the M37 manuals printed in the 50's gave specific instruction in the operator maintenance section to check oil levels in gear boxes frequently? It was because the authors of the manuals knew there would be leaking going on, thus the need for frequent checking an absolute necessity. These days there are better options than in the early 50's; not only in seal technology, but in lubricating oils as well. In todays best quality lubricants, seal swellant technology is a big deal and is a vital component in additive packages blended into oils so seal material stays pliable an flexible. These additives are designed to work with today's seal material, not 50+ year old leather material. These additives certainly have some adverse effect on leather, very possibly causing it to deteriorate at an even faster rate, or just not work well at all from the get go or soon afterwards. We've used properly prepared new leather seals, (not NOS) only to have a huge oil puddle under the diff in the morning. Leak issues range from annoying drips to huge puddles, either one is not good. This is what prompted me to design our pinion seal upgrade kit, it is very embarrasing to send out a professionally rebuilt or restored truck with oil leaks. For us, leather seals are simply not an option.