Why Does Gear Oil Smell So Bad?

oldmodman

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Gear oil smells terrible.
Regular and synthetic oil smell great (or at least they don't stink)
What is the component, or components, in gear oil that have such a terrible and impossible to get off you hands reek.
 

UnleashedBeast

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If I recall correctly, you are smelling the extreme pressure modifiers in the formulation.

They reek of sulfur.

Sulfur compounds are part of the extreme pressure lubrication additive pack needed by hypoid gears. Hypoid gears are found in rear-drive differential ring-and-pinion sets where the centerline of the pinion is offset below the centerline of the ring gear- it allows for the driveshaft to be lower and the floor of the car to be flatter. The gears themselves therefore are sort of halfway between normal straight-cut bevel gears and a worm gear. That means that as the teeth engage and release, they brush across each other while under high pressure. Special additives are needed to keep the specially hardened surfaces from degrading under that kind of contact. Its a bit like flat tappet cams where you have a sliding motion and high pressure at the same time, although not quite as extreme as the tappets.
 
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Jimmysidecarr

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If I recall correctly, you are smelling the extreme pressure modifiers in the formulation.

They reek of sulfur.

Yep it's the sulfur component in the extreme pressure additive.

Not sure I agree with this though..:dw::shrug:
Quote:
Its a bit like flat tappet cams where you have a sliding motion and high pressure at the same time, although not quite as extreme as the tappets.

If flat tappet cams were more extreme than a ring and pinion they would need an extreme pressure additive. Yet they don't they just need a bit more of the standard zinc and phosphorous (ZDDP) type anti wear additives.
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'03snkbt

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thought it was more the modifiers rather than the oil itself? friction modifiers smell like ass!!!
 

Jimmysidecarr

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thought it was more the modifiers rather than the oil itself? friction modifiers smell like ass!!!

That they do!
But the extreme pressure additive in a GL5 gear lube is going to be the source of the sulfur smell.

The older blue Ford friction modifier smell was particularly hideous.
The newer clear stuff is still bad but not nearly as bad as that blue stuff.

Almost like dead fish!:dw::nonono::xpl:
 

oldmodman

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The older blue Ford friction modifier smell was particularly hideous.
The newer clear stuff is still bad but not nearly as bad as that blue stuff.
Almost like dead fish!:dw::nonono::xpl:


That is PRECISELY what I got all over my hands last weekend. I knew I should have worn gloves, but I was just too damn lazy to walk over and get them.
Been three days and I can still smell it on my hands. I was taking apart an old (at least twenty years) 9" Ford diff that a friend gave me.
 

Jimmysidecarr

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That is PRECISELY what I got all over my hands last weekend. I knew I should have worn gloves, but I was just too damn lazy to walk over and get them.
Been three days and I can still smell it on my hands. I was taking apart an old (at least twenty years) 9" Ford diff that a friend gave me.

You are going to have to wait until the skin wears off.... LOL!:dw::-D:
 

03dsgdreams

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Lol I know the smell as well.. put a 4.10 in my old 99 cobra and had to use that blue ford friction modifyer. I did the work in my parents garage and they were not happy about it, the garage smelled horrible for months.
 

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