Stick with MT-90 or switch to Mobil 1 gear oil?

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This is for my 2008 Scion xB. I'm currently using Redline mt-90 (20k miles on the fluid) and the gears are just not going in as smooth any more. It use to be it be ok once it warmed up but now even at full operating temperature, the tranny still doesn't go in to gear as easily as it did. I read some where that the stock factory fluid and mt-90 don't mix well, maybe that's why it's acting the way it is (It's only had one tranny fluid change). Anyone think dumping the existing mt-90 and using fresh mt-90 would help solve this problem? The other idea I had was trying the Mobil 1 75w-90 gear oil to see if the problem goes away. Anyone hear tried it? It's fairly cheap and available at the local auto parts store which is a plus, but I couldn't find any threads about this stuff when I searched. The owners manual says I can use both GL-4 or GL-5 fluid.
 
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Originally Posted By: simple_gifts
Did you try the MT-90/MTL mix? I've used that for about 130K and have no complaints.
I have not, but I have read about people using this combo with good results. My tranny takes about 2.5-3 quarts of fluid. Should I do 2 mt-90 and 1 MTL?
 

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Originally Posted By: brandini
Do you have yellow metals in your trans? Make sure any fluid is MT-1 or it won't play nice with them!
I dont think so...If it did Toyota wouldn't mention GL-5 fluid in the owners manual right?
 
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I've heard about people using the MTL and MT90 mix. Believe it or not, I've had better luck with changing the oe manual fluid often than I have with the aftermarkets. I know that sounds weird. I used MTL in a Focus, and my older Mitsubishi because it claimed to be the same weight as required. I noticed that cold shifting was not the same, and that there was more gear noise, especially during down shifting. I ran Amsoil Manual fluid in my 06 Eclipse 6 spd for about a year, and I went back the the factory fluid. And for some reason it just feels like it works better. I have a 5gal bucket of the Mitsu oil so I just change it every season. Again this is weird because it is not a Synthetic oil,and I would have figured more engineering and performance went into the design of the Redline and Amsoil.
 

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Originally Posted By: aquariuscsm
Don`t use the M1 75W90. It`s not made for synchronized manual trannies.
Did not know that, thanks for saving me $30. lol
 

A_A_G

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Originally Posted By: aquariuscsm
Does your owners manual and/or FSM spec a 75W90 or a 70W80?
Straight from the manual: Gear oil API GL-4 or GL-5 SAE 75w-90
 
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Your Scion will NOT like the GL5. Run 2 MT90 and 1 MTL. I am currently running that combo in my Matrix 6 speed and it works well. MT 90 usually gets better after the second run.
 
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I had Mobil 1 75w-90 in the Aisin box in my Jeep and it shifted just as well as it does with the MT-90 that's in there now. The only reason I changed it is because I heard that for my MY transmission, you shouldn't use GL-5 fluid. It's still pretty rough, but I don't think the stock fluid was changed for the first 155K of the Jeep's life. When I drained it, the fluid looked liked metal Mario. When I bought it, it needed a double clutch to get into 1st or 2nd gear while moving, now it can be driven mostly normally, even if the shifts into 2nd and 3rd are a bit rough.
 
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Originally Posted By: A_A_G
Originally Posted By: aquariuscsm
Don`t use the M1 75W90. It`s not made for synchronized manual trannies.
Did not know that, thanks for saving me $30. lol
You bet bro! Man that stuff has gotten expensive!!!!!! I emailed them one time and thet`s what they told me,do not use it in a synchronized manual transmission. It`s strictly a rear differential oil. If you`re not happy with the MT90,maybe you should give Amsoil MTG a try. It`s amazing stuff!
 
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A_A_G

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Originally Posted By: aquariuscsm
Originally Posted By: A_A_G
[quote=aquariuscsm]
If you`re not happy with the MT90,maybe you should give Amsoil MTG a try. It`s amazing stuff!
I've thought about it but all the reviews I've read on it from people who have used are more negative than positive. People say the mt-90 is better than the amsoil stuff.
 

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Originally Posted By: wantin150
Your Scion will NOT like the GL5. Run 2 MT90 and 1 MTL. I am currently running that combo in my Matrix 6 speed and it works well. MT 90 usually gets better after the second run.
Thanks for the info, I think I'm going to go this route smile2
 
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I don't think that the MT-90 is better than the Amsoil, I just think that some applications work better with some fluids than others.
 

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Originally Posted By: Johnny248
I don't think that the MT-90 is better than the Amsoil, I just think that some applications work better with some fluids than others.
I agree, I guess the wise thing would be to stick with what has worked up to now. Maybe it's just time to change it out since it worked great up until recently.
 
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FWIW, I tried the MTG in my Matrix and did not like it as much as I do the MT90 and then the MT90/MTL mix. Even with that mix, I will get a 2 to 3 grind which I attribute more to a syncro issue than the fluid as all other shifts are very smooth. The "grind" only happens when the temps fall below 60F and the fluid is cold. I can ease the shifter into 3rd and all is well. Just have to remember to do it. The 6 speed in the Matrix is known to have that 3rd gear syncro issue.
 
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