Weights

[mjoekingz28]

I've been thinking for years that a 10w is heavier than a 5w, it seemed like common sense. A weight is a weight, so why does Redline (also RP's stuff)say:

(regarding some 75w90 API GL-4 Gear oil I just got)



" Satisfies the gear oil viscosity requirements of 75w, 80w, and 90 and MOTOR OIL VISCOSITIES SAE40, 10W40 AND 15W40"


How can a 75w be the same viscosity as a 10w40?

I don't get it.

 

[OilGuy]

Different units/scales. 12 inches equals 1 foot (different units, same length). We understand length comparisons, but viscosity scale comparisons are foreign.

 

[Pablo]

Indeed different scales.

Try this: http://www.bobistheoilguy.com/visc.html

 

[mjoekingz28]

Aight, so 10w40 can be the same viscosity, weight and thickness of a 75w gear oil.

Same weight of oil, just different numbers?

 

[mechtech2]

Motor oil is measured at 200F.
Gear oil is measured at 150F.
So the same viscosity will be thicker at 150. Hence the gear oil is rated heavier .

 

[Pablo]

Originally Posted By: mechtech2
Motor oil is measured at 200F.
Gear oil is measured at 150F.
So the same viscosity will be thicker at 150. Hence the gear oil is rated heavier .


What? Got proof?

http://www.lubrizol.com/products/automotive-gear-oil/J306.asp

http://www.infineum.com/information/api-viscosity-2004.html

 

[bruce381]

NO motor oil is messured at 100C thats 212F
Automotive gear oils are also messured at 100C

Industrial gear and hydrualic oils are messured at 40C.
bruce

 

[XS650]

Originally Posted By: bruce381
NO, motor oil is measured at 100C thats 212F
Automotive gear oils are also measured at 100C

Industrial gear and hydraulic oils are measured at 40C.
bruce


I added a coma.

 

[G-MAN]

Originally Posted By: mechtech2
Motor oil is measured at 200F.
Gear oil is measured at 150F.
So the same viscosity will be thicker at 150. Hence the gear oil is rated heavier .

 

[Pablo]

Originally Posted By: XS650
Originally Posted By: bruce381
NO, motor oil is measured at 100C thats 212F
Automotive gear oils are also measured at 100C

Industrial gear and hydraulic oils are measured at 40C.
bruce


I added a coma.

So - punctuation (and spelling) does matter!! (so does being out for awhile - comma

) On a serious note, the above wrong reply tells you to beware of a few lines on the internet.

 

[TallPaul]

If my manual says to use a 20 weight, does that mean I can run 20w50?

 

[bruce381]

No spell check or grammer check on this site
I need it. LOl

 

[bmwtechguy]

Some folks are really good at spelling and typing, others are not. I'm used to Bruce's errors. The info is still good even if the spelling and sentence stucture are not so good.

 

[Pablo]

Yeah I'm OK with Bruce - I knew what he meant. I just couldn't resist when XS650 wanted to put him in a coma. Meanwhile mechtech2 walks.........

 

[TallPaul]

Originally Posted By: TallPaul
If my manual says to use a 20 weight, does that mean I can run 20w50?

Now how did this get here. I meant to post it in the 5w20 thread. Must have had too many wondows open.