Even after giving my friend the "How can the little oil company make better oils than the big guys?" speech/question. Maybe the big guys are better stretching their oils to make a bigger profit.

Today I bought some Redline MT-90 manual transmission gear oil. It is a GL-4 75w90, as spec'd in the manual. Here is what Redline claims "Appropriate coefficient of friction for most manual transmission synchronizers (other's synthetic gear oils are often too slippery for proper synchro engagement)" and "Safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage" More info here http://www.redlineoil.com/product.aspx?pid=46&pcid=7 I had to buy it at a race shop, 3R Automotive.

I'm changing all my 4runner fluids tomorrow and was short some oil so I wanted to give this a try. My MT is getting a little notchy and hard to shift sometimes. It is suppose to help. I have also heard that it will take a few days. Only time will tell.

There must be differences in gear oil because there are about a dozen different types that Redline makes. Some for diffs some for transmissions.

Updates to follow.
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UPDATE

Today I changed the oil in my transfer case/front diff/rear diff (used a full synthetic 75w90) and my manual trans (using Redline MT-90)

The MT-90 is different. You can tell that it doesn't have the sulfur that a GL-5 has. It has a noticeably different consistency. It really flows (as in, appears to be very thin) and of course it has a red tint to it.

I had heard that gear oil and motor oil is rated differently. I had also heard that a 90 weight gear oil is about the same viscosity as a 40 weight motor oil. The MT-90 states that it "satisfies the gear oil viscosity requirements of 75w, and 90, and motor oil viscosities SAE 40, 10w40, 15w40." Interesting!

I'll update with my opinion after driving for a week or so.

FYI (75w90, the 75 is the cold/winter viscosity and the 90 is operating viscosity, the w=winter not weight)
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UPDATE

This stuff is amazing. My 4runner is shifting better than ever.

The repair manuals say that you can use a GL4 or GL5 in the manual trans. The GL5 is high is sulfur which is what diff gears need but is hard on the brass parts in transmissions. If it says use a GL4 then use a GL4.

 

Im also running MT90, its some good stuff!

 

Correct, Toyota lists GL-4 or GL-5 oils in the transmission, this basically means GL-5 oil addives won't hurt anything. But GL-4 oil will work better since it was designed to work in things like manual transmissions. GL-5 oils are slipprier to work with things like ring+pinion gears where you have heavy loads with sliding/shearing friction. But it is those same slippery additives in the GL-5 oil that plays havok with the synchromesh rings in the transmission. Kind of like the difference between the Formula 1 races cars when the race course is wet and some cars are on slicks and some on rain tires. F quick, smooth shifting, you want those synchro rings to grab and spin up their gear shaft quickly and with a slippery oil, they slip and take longer to spin up and thus shifting is more sluggish and rough.

 

What is your mileage at? I was going to be doing all the powertrain fluids in the next week or so and didn't even think about the Redline this time around (though there has been much discussion on it since my last drain and refill).

Did you fill the transfer case with the Redline, too?
If I remember correctly, both the transmission and transfer case call for the 75w90 (funny they differentiated the "w" from the standard "w" in their product...)

 

Thanks for the review. My tranny in my '00 is also shifting a little notchy and I figued it was time to change the fluids. tranny has 107K on it. How many quarts do the trannys take?

 

i'm curious if anyone has made the change to redline from amsoil, and if so, what difference it made.

 

4 year old thread, but thank you for taking the time to do a good review. I just ordered my MT-90!