What oil for MT 6?
 

I bought 2 quarts of redline MT-90 and 2 quarts of MTL, this should give me about a 72.2W85 oil. The spec is 75W85.

Is that right?

So you're planning to mix them? Then what? What are you going to put it into?

I am going to put it into the transmission!

I just used straight MT-90. What's the rationale behind mixing them?

I think people mix the MTL in to make the oil a little thinner for low temperatures and improve cold shifting. MTL has less than half the viscosity of MT-90 below 100 degrees.

MT-90 is 75W90 and MTL is 70W80. So I do not think MTL is half the cold viscosity of MT-90. 70 vs 75.

It is. The gear oil weights are weird.

MTL is the equivalent weight of 5W30 engine oil.
MT-90 is the equivalent weight of 15W40 engine oil.

MTL viscosity at 40C : 56 cSt
MT-90 viscosity at 40C : 90 cSt

There's even more disparity at room temperature or below.

wasn't there a guy that ended up with 10oz in his engine? :D