I got my gearbox rebuilt 2500 miles ago and put in the MT90. Want to change it in an other 1000 miles just for GP.
Anyone have experience with both brands in their 5 speeds??

I have redline MT90 in my trans.. I noticed that the shifting is much smoother with this fluid in.

I have used the regular Amsoil GL-4, Series 2000 GL-4, and Redline MT-90.

In terms of smoothness I like from best to least:
Amsoil Series 2000
Redline MT-90
Amsoil "regular" GL-4.

Since they discontinued the Series 2000 GL-4 I'd get the Redline MT-90 over anything else. So in your case just stick with MT-90.

I put mobil 1 in mine. I didn't notice a difference and infact I have heard that this is not such a good idea...Too much sulfer or something. I plan on switching to Redline MT 90. Just my $0.02.

Get that Mobil 1 GL-5 crap out ASAP. It will eat your soft metal parts. GL-4 only for Nissan Transmissions.

The only reason I didn't go with AMSOIL's Marine is their 80W90 rating vs. the discontinued series 2000 75W90. I wanted the extra 15 degrees pour temps the 75 weight gives for danm cold winters. I want to make sure that shi!t flows! AMSOIL doesn't have a GL-4 in 75 weight any more. Went to Redline MT-90, but I also considered (mostly cause the BOBISTHEOILGUY demo) giving Schaeffer's 267 supreme gear oil a shot, but it's a syn blend and 80W90 too. They claim it's safe on the yellow metals even though it's rated GL-5. The demo almost sold me on it.

I have Amsoil Series 2000 75w90 and I didn't notice much performance difference between that and the oem stuff. Since the Amsoil Series 2000 has been discontinued, their new Severe Gear oil is apparently a good substitute.

Except Severe Gear is GL-5 rated (not GL-2 thru GL-5 like the Series 2000 gear oil) and it shouldn't be used in applications specifying GL-4...

I went from the Amsoil marine gear lube to MT-90, and the MT-90 is much better in terms of smoothness and low temperature viscosity. I've never tried the Series 2000, but since it is discontinued I guess that doesn't matter.

Thanks Mizeree X....that's comparision I was looking for....

Ahh I didn't know that. Thanks for the info, looks like I may be going to Redline now then.

Wrong answer.
Call Tech Support@Amsoil
SVG can be used where GL-4 is specified. It has the protectant for the soft "yellow" metals.

If this can be used for the GL-4 application like someone mentioned, does this fluid have the friction modifiers for VLSD operation?

I do not believe it has it.

I've asked the question as you recommended. I'm curious to hear what they have to say since SVG is not labeled for GL-4 applications like the previous TGR, AGR and AGT oils were.

I did call AMSOIL Tech Services and ask if GL-5 Severe Gear can be used in GL-4 applications (even though it is not labeled as such). I'm sure you're aware of the difference between GL-4 and GL-5 lubes so I won't go into that. But, the individual at AMSOIL told me that Severe Gear contains a "more aggressive additive package" than the previous products (clearly labeled GL-2 thru GL-5), and although some people are using Severe Gear in GL-4 applications, AMSOIL does not recommend it. For GL-4 applications, AMSOIL recommends 80-90 GL-4 (AGT/ALU).

I have been selling AMSOIL products for a very long time and I am very conservative on the products I recommend...I have learned that when in doubt, refer to the product label. If AMSOIL intended for this oil to be used in GL-4 applications, they would have labeled it as such.

Use what you want; but if in the long term you have a problem with it, please don't blame the oil.

I have been doing a lot of reserch since it appears that, in the GL-4 category, Redline MT-90 is pretty much the onlly full synthetic choice in 75W-90. Has anyone tried or even heard of Silkolene Silktran Syn 5? It's a pricy ($13 a liter) British import compatible with GL-4/5 apps.

I used MT-90 on my MR2. Slight gear grinding went away. Haven't really noticed anything w/ Amsoil except the fact that draining after 50k miles, it still looked new.

You may refer to the product label, and I do as well. Three calls to Amsoil and 2 different stories. I am taking SVG out. Ron this morning told me that it is not recommended. When I was in the market for it, I was told it was recommended by 2 individuals from Amsoil. As a dealer myself, I have loged a complaint and it in their tracking system.

Seems like the story has changed. I am very disappointed.

From the Amsoil spec sheet:

"Use in differentials, manual transmissions or other gear applications where one or more of the following standards are specified: API GL-5 & MT-1, MIL-PRF-2105E, Dana SHAES 234 (Formerly Eaton PS-037) for 250,000 miles, Mack GO-J, Arvin/Meritor 0-76N (75W-90) & 0-76M (75W-140), plus hypoid gear oil specifications from all foreign and domestic manufacturers such as GM, Ford and Daimler Chrysler. Can also be used in rear axles where API Service GL-4 lubricant is recommended."

I am yet to find a rear axle that is made of soft, yellow metals. The issue in our case is care of the synchonizers, not the differential.

There is another alternative which I found to be better than my prior Redline product (MT-90) and that is Royal Purple synthetic 75W90: I just changed to this fluid this past Saturday and shifting is noticeably smoother than with the Redline and it's approved for GL4 use......

Not cheap, though...almost 11 bucks a quart...