I've been following this thread for the last few days, and since my sister is a
PhD research chemist for Lubrizol (they make additives for lubrication
products) I thought I'd ask her what ingredients in the lubes attack metal.
She responded:
"Many gear lubricants contain sulfur compounds which help protect
iron-containing metals compounds from wear. Unfortunately, these types
of compounds do not protect so-called "yellow metals" (alloys containing
copper) and may, under certain circumstances, be detrimental to parts
made from these materials. However, some lubricants contain additives
to protect yellow metals in the sulfur compounds. This will vary
between lube oil brands and applications - gear oils are formulated
differently than heavy motor oils, for example. The user will have to
contact the lubricant manufacturer to get information on the
applicability of a given oil to systems containing certain metals to
know for sure."
She also told me that motor oils do contain sulphur componds which attack
yellow metals, but contain those additives she metioned above that protect
copper alloys. Thus motor oil in the gearbox won`t eat brass as a GL-5 fluid
might. Her bottom line is each manufacturer's compounding is different, so be
sure to ask them if the product is detrimental to yellow metals.
I hope this helps.
Bruce "Electrical Engineer Stuck In A Chemist`s World" Clough
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