Is MTL okay for the Trasmission, even though it's a 90 weight??

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I Grok NSX

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Okay, I've read the Maintenance section of the FAQ and also found this link: http://www.nsxsc.com/ubb/Forum17/HTML/000030.html
My question is why is it okay to use Redline MTL, which is a 75W-90 weight oil but the Honda manual says to use a 10W-40 weight?

In reading the above link, it states that "Red Line MTL is classified as a 70W80 gear lubricant satisfying the API Service requirements of GL-3 and GL-4. MTL also satisfies motor oil viscosities SAE 5W/10W/30, and the viscosity requirements for ATFs. MT-90 is a 75W90 GL-4 and also satisfies motor oil viscosities SAE 10W/15W/40".

How can an oil be 75W90 but still be a 10W40 weight? This makes no sense to me. But I really don't want to understand, I just want to know if it is okay to use the Redline MTL for the transmission. I see others using it with good results, but I hate to deviate from the manual. I think Honda would know what's best for their products.

Please help. Thanks in advance.
 
Gear oil viscosities are quoted on a different scale from motor oil viscosities. Thus, when a gear oil says that it's 70W80, that means that its viscosity is similar to that of a motor oil that is labeled 10W30. Same thing with 75W90 gear oil and 10W40 motor oil.

In other words, you should be okay with the Redline (aside from the fact that it's rather expensive). You're probably better off with the MTL in northern areas, and the MT-90 in southern (warm-weather) areas.
 
I just changed the tranny oil in my 98 Civic. I used Redline MTL. Shifting from neutral to first is easier, shifting from fourth to fifth is easier too, but no other changes were noted. Changing the tranny oil in the NSX Friday when the speed shop gets a new shipment in. Thanks for the help.

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1994 Green-black roof/tan, 5 speed
Stock as a rock - #0030
 
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