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Has anyone used amsoil 75w90 gear oil in the 5-speed tranny? What is
different or special about Honda manual transmission oil? :D I understand the amsoil gear oil increases fuel mileage.
 

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For the syncros in the manual transmission to work properly, a certain amount of friction additives is required. Synthetic gear oil is designed to minimize friction as much as possible for gears and it is much more successful at that then petroleum based gear oils.
Using the fantasticly slippery amsoil gear oil will wear out your syncros because they will slip much more instead of engaging quickly. It's best to use Honda's own manual transmission oil.

I've inquired with the hardcore racers at HADA club (honda acura drivers assosiation) about transmission oils. Most have tried specialty synthetic transmission oils like Redline, Motual etc.. and even fords heavy duty transmission oil. The conclusion is that almost all of them have found that the Honda trasmissions work best with the Honda transmissions.

Keep in mind that all these guys use synthetic engine oil because there is no question that it's significatly better then petroleum engine oils including honda's own.
 

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Honda MTF is a synthetic blend of the 40 grade range. The 75w-90 grade you are proposing will cause stiff shifting and gear clashing, its just too thick. AFAIK Honda has never used the 75-90 higher viscosity grade oil in any of their transmissions.

An alternative to Honda MTF is a 10w30 or 10w40 full synthetic motor oil. Although Honda has published "warnings" about using such in the past. Its too slippery in some circumstances / driving patterns / conditions and can allow gear rake. You'll hear / feel it (the synchro slips too much when shifting).

ALthough I am using and have used full synthetic in the past and in several Hondas without incident for over 200K miles.

HTH! :)
 

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Forget the 75W90 gear oil. As John suggested, it is definately too thick! In cold weather it will feel like you have corn syrup in there!

Again, as John suggested, try 10W40 or stick with MTF.
 

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Below is an email sent to Amsoil and their reply concerning a fluid for the 5-speed.

Currently my dealer says that an Amsoil lubricant for the manual transmission on my 2000 Honda Insight is not available. Will you have anything in the future? I use Series 2000 0W30 in the engine with favorable efficiency results (Honda recommended 0W20) and would like to use Amsoil in the trans as well. Thank you,


From: AMSOIL Technical Services

Thank you for contacting AMSOIL with your concerns.

In response to your inquiry, yes the driveline fluids folks are looking at a manual transmission lube for Honda/Acura vehicles. We don’t have a time line yet though.



Thank you again for the opportunity to respond to your concerns. As always, please feel free to contact us again if we can be of further assistance.



Sincerely,



Jim Van

AMSOIL Technical Services
 

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Redline MT-90 fluid is very good, and they work fantasticly in Subarus etc..
The Redline MTL oil is designed for transmissions like the Hondas so it will work well, and maybe improve mileage slightly in winter.
But the honda racers I spoke with said the honda transmissions shift better and faster with the Honda MT fluid then with Redline MTL.

YOu can try it, it will do no harm.
 

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MT90 is a 90W range oil it will cause shifting problems. (I have personally seen it tried in other Hondas)

I have also seen Honda MT's misfilled with dino 90w's with damaging results. The synthetic 75-90w range oils _may_ have sufficently better properties beyond their dino cousins that prevent this.

The tolerances in a Honda MT are simply too "tight" for 75w or heavier oils to flow.

Stick to the 10w-30/40 range.

HTH! :)
 

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I recently changed my MTF at 30K miles with new Honda manual transmission fluid (which btw is cheaper then 0W-20 oil). I know this was half the recommended interval, but even after 30K new fluid made a noticable difference.
 

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Isn't 10W30 viscosity in motor oil is equivalent to 70W80 viscosity in gear oil? I've run across a couple of gear oil descriptions that say a 70W80 gear oil is 10W30 motor oil with transmission-specific additives.

MTL is 70W80, so it's as least the same viscosity as the Honda MTF if the above is correct.
 

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I tried Redline transmission oil in Miata one time because when the transmission is cold, it's tough to get it into first gear. ("They're all like that.") I went back to the recommended dino oil because while the Redline stuff made it a bit easier to shift when cold, it was too thin when warm. You could beat the synchronizers pretty easily.

My view is that the car companies pay their engineers big bucks to design the cars, and that the best thing to do is what the engineers say. Speaking as an engineer... :)
 

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John Stimson said:
Isn't 10W30 viscosity in motor oil is equivalent to 70W80 viscosity in gear oil? I've run across a couple of gear oil descriptions that say a 70W80 gear oil is 10W30 motor oil with transmission-specific additives.

MTL is 70W80, so it's as least the same viscosity as the Honda MTF if the above is correct.
Sorry John, no.

SAE's viscosity index is just that. There's no different index for different types of oil. When you see such numbers its the same viscosity system being used there's no "conversion" factor. It must be the addatives that increase the viscosity. ;)

You may be mixing up the viscosity of ATF (which generally dosen't carry an SAE viscosity rating). And you'd be correct that Dexron ATF is very close to 10W-30. But a major ATF limitation is the oil film's shear strength. Under extreme "stress" conditions ATF will _not_ give the same protection that engine oil does in a manual transmission. Major damage will ocurr usually in only a few hundred miles if 30 weight is substuted for 80W or vice versa (depending on the transmission's viscosity requirements).

HTH! :)
 

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Sorry Dougie,

You are correct that there may be some technical difference, I was going from hands on. Simply pour and feel the difference. It seems to be about twice as thick. But I haven't looked at the technical definition of viscosity in a long time.

What I am absolutely sure of is that _any_ Honda MT that is fed 80-90W _will_ fail from lack of adequate lubrication, and its's not pretty :!: ;)
 

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i know this is an old thread..... but..........


i'm going to try an put in some Redline 75w80 "MTL" in my 2006 Insight, as opposed to the stock OEM Honda tranny fluid

car had nice fresh oil in it upon changing it over, so the comparison should be pretty easy to make. i'll check back in within a month or so and let you all know if it shifts/feels any different w/ the Redline instead of the Honda fluid
 

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i'm going to try an put in some Redline 75w80 "MTL" in my 2006 Insight, as opposed to the stock OEM Honda tranny fluid
That would be great to know any differences. I felt a difference from old to new stock fluid making for smoother shifting.
There's a couple others: Castrol VMZ80, Amsoil ATF, as well as the Redline MTL that match the specs of the Honda MTF. Specs for fluid in lower left corner of linked photo.
 

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so what is Hondas viscosity? I presumed it was like 10-30 or something close as they said you can use motor oil as a substitute (just needs more changes). That's what I have been using
 

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personally coming from a honda enthusiast background and in my s2000 i've been using gm synchromesh fm, and i have a 2000 w/ 181k that has the 3-2 downshift grind. it didn't help the grind at all but it shifts smooth and quick.

anyone have experience with gm synchromesh fm
 
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