Gear oil & motor oil base fluids

[bulwnkl]

Okay, I've run some searches, but I'm not finding info that's on-point. Is there an inherent difference between the base fluid(s) of a gear oil versus a motor oil?

This question relates to MTX fluid choice in an application where a light (eg. 75W85) gear oil OR a fluid described as having a 5W30 motor oil "base" could be used. Is there a difference? What is the significance of any differences?

 

[mechtech]

Motor oil and gear oil are rated at different temperatures. That's why a gear oil seems to have such a high viscosity rating.

 

[bulwnkl]

Thanks. Do you know whether there is anything different about the fluids themselves?

 

[y_p_w]

quote:

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Originally posted by bulwnkl:
Thanks. Do you know whether there is anything different about the fluids themselves?

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Base fluid? Probably not. Additive pack? Absolutely. There are great gear oil additives that would never survive inside the crankcase.

Honda stopped specifying 10w30/10W-40 motor oil for their manual transmissions years ago. Something about relying on a good dose of ZDDP for gear protection.

 

[Ken2]

quote:

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Originally posted by mechtech:
Motor oil and gear oil are rated at different temperatures. That's why a gear oil seems to have such a high viscosity rating.

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Not quite right.

They put 0 to 60 numbers on motor oil to identify it as motor oil. 75 to 250 numbers are on gear oil to identify it as gear oil. 70 sometimes goes either way.
http://www.lubrizol.com/ReadyReference/DrivelineLubricants/15-gears/default.asp
http://www.infineum.com/information/viscosity.html


Ken

 

[VaderSS]