Why is synthetic 75-XX ?
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It flows better when cold.
Actually, I believe its to "separate" the product a little better. There are 80w90 synthetic and mineral gear oils. But, when you buy a 75w90, you're almost always getting a synth or blend. It makes it easier for the simple minded consumer to pick what is needed.
Actually, I believe its to "separate" the product a little better. There are 80w90 synthetic and mineral gear oils. But, when you buy a 75w90, you're almost always getting a synth or blend. It makes it easier for the simple minded consumer to pick what is needed.
MolaKule
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As unDummy said, it's just the recognition factor and because the synthetics have a higher VI or wider operating temp range. You can make a 75W90 from mineral oil but you need a lot of viscosity index improver.
One could make a 50W150 from Synth if you wanted.
We make a 90W120 for racing, but since people aren't familiar with those numbers, we just say, "Mid-Viscosity" Racing lube.
Check out this article to see what gear lubes might contain:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000226#000000
One could make a 50W150 from Synth if you wanted.
We make a 90W120 for racing, but since people aren't familiar with those numbers, we just say, "Mid-Viscosity" Racing lube.
Check out this article to see what gear lubes might contain:
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000226#000000
Molakule, I thought your Mid-viscosity oil was supposed to be about 75w-120. Looking at the spec sheets you have posted, it's cold flow at 40c is right between the 75w/90 & 75w-140 and it's pour point is at a lower temp than both of those. So anyway, I'm a bit confused.
Hammer
Hammer
"So anyway, I'm a bit confused."
me too what hot end vis is a 120 or a 150?
bruce
me too what hot end vis is a 120 or a 150?
bruce
SAE doesn't have enough numbers for oil weights. IMO, they need to add more "ranges" for certain fluid weights. Look at the number of different weights for motor oils and compare it to the gear oils.
Don't forget that the 80 and 85(now common) gear oil weights were unheard of a decade ago, and I believe only added in the '98 revision.
Any MFG that wants to differentiate their products because they are blending it a little thin or thick, will sometimes make up their own numbers.
For example, there is a 3w30 motor oil. But, SAE only list 0w30 or 5w30. I've also seen 7.5w30 and believe that it too was a MFG spec or other country spec(not SAE).
I actually like the idea of that '120'wt SF spec. It falls nicely in between the 90 & 140 weight gear oils, which, IMO, is too big of a gap.
Don't forget that the 80 and 85(now common) gear oil weights were unheard of a decade ago, and I believe only added in the '98 revision.
Any MFG that wants to differentiate their products because they are blending it a little thin or thick, will sometimes make up their own numbers.
For example, there is a 3w30 motor oil. But, SAE only list 0w30 or 5w30. I've also seen 7.5w30 and believe that it too was a MFG spec or other country spec(not SAE).
I actually like the idea of that '120'wt SF spec. It falls nicely in between the 90 & 140 weight gear oils, which, IMO, is too big of a gap.
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