Which 75W-80 gear oil for manual transmission?

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Originally Posted By: badtlc
Originally Posted By: inquirer

So what's the deal? I am asking because I already use one of these oils...


It is a better safe than sorry approach. Many GL-5 fluids have destroyed synchros. Some newer GL-5 fluids claim they are yellow metal synchro safe and they probably are. But a safe general recommendation would be to avoid them.

I think Molakule can recommend dual rated GL4/GL5 fluids that are safe for yellow metal synchros. Motul might have been one he recommended previously. I know Fuchs was one of them.


The thing is when a company like Motul (which undoubtedly is a huge reputable company) states explicitly that their GL-4/GL-5 oil is OK for synchronized gearboxes should it be trusted or not? What should I decide as a consumer?

For example for the Motylgear 75W80 which I use Motul states:

"Technosynthese® lubricant designed for all mechanical transmission, synchronised or not synchronised gearboxes, gearbox/differential and transfer gearboxes without limited slip system operating under shocks, heavy loads and low revolution speed or moderate loads and high revolution speed. "



Originally Posted By: supton
Originally Posted By: 29662
Redline MTL. I use Redline MT90 in my Toyota and I can say that it's very possibly the best gear oil I've ever used in a manual transmission.


I have MT90 in my Camry, and I need to wait for summer before I condemn it. But it's definately the wrong stuff for winter.


Is it the right grade? I did a quick search for a random Camry using Red Line's application guide and it recommends the MTL, not MT-90...
 
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Originally Posted By: inquirer


The thing is when a company like Motul (which undoubtedly is a huge reputable company) states explicitly that their GL-4/GL-5 oil is OK for synchronized gearboxes should it be trusted or not? What should I decide as a consumer?

For example for the Motylgear 75W80 which I use Motul states:

"Technosynthese® lubricant designed for all mechanical transmission, synchronised or not synchronised gearboxes, gearbox/differential and transfer gearboxes without limited slip system operating under shocks, heavy loads and low revolution speed or moderate loads and high revolution speed. "


That is a great question. Maybe contact the company directly if you trust them? I'm not sure if all synchronized transmissions use yellow metals but that is the main concern. I'd ask them if it is yellow metal safe or maybe find out if your transmission doesn't use yellow metals. If your car spec'd GL-4 or lower, I'd think it is a safe assumption it uses yellow metals.

This data sheet does say it is yellow metal safe: http://www.motul.com/system/product_descriptions/technical_data_sheets/143/Motylgear%2075W-80%20(GB).pdf?1328624012
 
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Originally Posted By: inquirer
@badtlc

Good catch! Thanks for pointing that out!


Glad I could help!
 
Again, while Motul and Fuchs are reputable companies
why bother using a dual rated GL spec where there are
dozens of GL-4 only spec products (especially in Europe)
which will be perfect for the job.

Perhaps you missed what I posted above which is
what the SAE says regarding GL-4 and GL-5 specifications...
The two specs are not interchangeable and
and GL-4 is NOT superseded by GL-5.
 
Originally Posted By: antiqueshell
Again, while Motul and Fuchs are reputable companies
why bother using a dual rated GL spec where there are
dozens of GL-4 only spec products (especially in Europe)
which will be perfect for the job.

Perhaps you missed what I posted above which is
what the SAE says regarding GL-4 and GL-5 specifications...
The two specs are not interchangeable and
and GL-4 is NOT superseded by GL-5.


I actually didn't miss it. But I've already filled the gearbox with a Motul product. Years ago... At that time I didn't know there was this issue with yellow metals. I just followed Motul's guide which suggested the certain product for my car. As badtlc pointed out Motul refers to yellow metals in the oil's datasheet, something I've missed myself.

Anyway, when a product is labeled as GL-4/GL-5 doesn't that mean it fulfills both standards' properties at the same time? Because if that's the meaning all GL-4/GL-5 oils would be safe by definition, if they carry all the properties of a GL-4 oil which is indeed safe as you mentioned yourself.
 
It doesnt make sense to use any labeled GL5 product in a transmission, no need for it. Others above are correct, one other thing not mentioned is the wear and tear on oil seals that GL5 MAY produce.
GL5 is made for differentials, use what your manual says, don not think you are doing good if it calls for a GL1 (motor oil) or GL4 gear lube and you put in a GL5.

BTW - GL1 is still a valid rating, GL2 and Gl3 is no longer. Pretty much GL1 is motor oil and a lot of transmissions use it.

Its kind of like, using a DOT 5 brake fluid is better then using DOT 4 brake fluid in a DOT4 system, a big no no.
 
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Originally Posted By: BMWR1150GS
Would some moly added to the gear oil quiet gears, reduce heat and improve shifting?

It did for me in my Getrag gearbox on my BMW motorcycle.


What type of transmission? Probably not in a synchronized passenger vehicle type MTX.
 
I can swear by the Redline GL-4 gear oil. Past few days here in Kentucky have been in the negatives (-22F yesterday) and the Redline GL-4 shifted like butter. Running the Redline GL-5 in the rear diff and transfer case. Good stuff.
 
OK if you say so. I'm using RL MT-90 in my ECHO and at -18 the other day it was pretty gooey.

Frozen butter, maybe...

Originally Posted By: PostalBound
I can swear by the Redline GL-4 gear oil. Past few days here in Kentucky have been in the negatives (-22F yesterday) and the Redline GL-4 shifted like butter. Running the Redline GL-5 in the rear diff and transfer case. Good stuff.
 
MT90 gets pretty thick when cold. For an Echo, consider the MT85. Even a 50:50 blend of MT85+MT90 in mine much better than straight MT90.
 
Oh, Ok. I just picked what seemed most appropriate from their website.

Originally Posted By: Greasymechtech
MT90 gets pretty thick when cold. For an Echo, consider the MT85. Even a 50:50 blend of MT85+MT90 in mine much better than straight MT90.
 
Originally Posted By: inquirer
Hi from Greece!
So which of these (or maybe another product that I haven't listed here) is the best (smoothest gear changes and top protection)?

Thanks!
[/list]


If your transmission calls for GL4 (GL3)......you can not put GL5 inside directly due cemical corosion of "non ferrous metals"......GL5 has stronger chemistry...

BUT you can put in or GL4(original spec).......or GL4+ GL4/5 GL5 with MT1 spec....those 3 are transmission oils with GL5 level of protection.....but with diferent chemistry wich is not attacking "non ferrous metals"...

So for best protection in GL4 gearbox I will put in Total with GL4+ specification
wink.gif


http://www.oilspecifications.org/api_gos.php
 
My go to for 75w-80's with reluctant shifting is either Total BV75w-80, or Castrol Syntrax B
 
I'm reviving this topic, because I may change gear oil relatively soon.

Are GL4+ and GL4/GL5 really forbidden for a car with a transaxle that requires a GL3 oil? I was thinking of TOTAL TRANSMISSION GEAR 8 which is listed as a GL4 in Total's website, but I think as GL4+ on the bottle.

On the other hand MOTUL MOTYLGEAR which is a GL4/GL5 oil, and the one suggested by Motul for my car, says:

Quote:
Suitable for any type of seal and yellow material used in gearboxes design.


So what should I do? Avoid them or not?
 
I'm going to suggest GM/AcDelco/Pennzoil Synchromesh. It's rated GL3 and it works fantastic in imports where a thinner oil like 75w-80 is specified. It is not synthetic but is known for great synchronizer performance. I've had better luck with this than RL MTL but YMMV.
 
Last edited:
Originally Posted By: inquirer
I'm reviving this topic, because I may change gear oil relatively soon.

Are GL4+ and GL4/GL5 really forbidden for a car with a transaxle that requires a GL3 oil? I was thinking of TOTAL TRANSMISSION GEAR 8 which is listed as a GL4 in Total's website, but I think as GL4+ on the bottle.

On the other hand MOTUL MOTYLGEAR which is a GL4/GL5 oil, and the one suggested by Motul for my car, says:

Quote:
Suitable for any type of seal and yellow material used in gearboxes design.


So what should I do? Avoid them or not?
Go for it.
 
@zeng

My understanding is also that there is no problem with GL4+ or GL4/GL5 oils. But I guess that Total's oil would be a semisynthetic, so I have started to thinking of Red Line MTL.
 
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