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GL5 MT1 in an Older Transmission #4556909
10/28/17 08:13 AM
10/28/17 08:13 AM
Joined: Oct 2008
Posts: 68
NY
redwolf4k Offline OP
redwolf4k  Offline OP
Joined: Oct 2008
Posts: 68
NY
Hello,

This may be one of the most clouded topics in regards to gear oil. In 2017, is a GL5 MT1 rated gear oil acceptable in a thirty year old brass synchro manual transmission?

GL5 gear oil is cheap nearly everywhere, GL4 gear oil is mainly from specialty brands and expensive.

I wanted to ask the pros here: GL5 MT1 = yellow metal safe?

Last edited by redwolf4k; 10/28/17 08:14 AM.
Re: GL5 MT1 in an Older Transmission [Re: redwolf4k] #4556918
10/28/17 08:26 AM
10/28/17 08:26 AM
Joined: Feb 2015
Posts: 2,194
Slovenia EU
Kamele0N Offline
Kamele0N  Offline
Joined: Feb 2015
Posts: 2,194
Slovenia EU


2011 Hyundai i30 1.4 CVVT Shell Helix Ultra 5w40
1997 Toyota Landcruiser KZJ95 3.0 TD Shell Rimula R6M 10w40
Re: GL5 MT1 in an Older Transmission [Re: redwolf4k] #4556972
10/28/17 09:36 AM
10/28/17 09:36 AM
Joined: Sep 2015
Posts: 2,256
Malaysia
zeng Offline
zeng  Offline
Joined: Sep 2015
Posts: 2,256
Malaysia
Originally Posted By: redwolf4k
I wanted to ask the pros here: GL5 MT1 = yellow metal safe?


Yes, a GL5 without MT1 = yellow metal safe. Period.
A GL5 with MT1 = more safe, if one must differentiates.

Re: GL5 MT1 in an Older Transmission [Re: redwolf4k] #4556991
10/28/17 09:52 AM
10/28/17 09:52 AM
Joined: Feb 2015
Posts: 2,194
Slovenia EU
Kamele0N Offline
Kamele0N  Offline
Joined: Feb 2015
Posts: 2,194
Slovenia EU
You are wrong.... GL5 solo is never yellow metal safe!

GL4+.... GL4/5...or GL5/MT-1 tends to be yellow metak safe...

Althouhg some yenks are saying that it is not so...in 21.st century


2011 Hyundai i30 1.4 CVVT Shell Helix Ultra 5w40
1997 Toyota Landcruiser KZJ95 3.0 TD Shell Rimula R6M 10w40
Re: GL5 MT1 in an Older Transmission [Re: Kamele0N] #4557068
10/28/17 10:52 AM
10/28/17 10:52 AM
Joined: Sep 2015
Posts: 2,256
Malaysia
zeng Offline
zeng  Offline
Joined: Sep 2015
Posts: 2,256
Malaysia
Originally Posted By: Kamele0N
You are wrong.... GL5 solo is never yellow metal safe!

What a bold and hilarious claim!
Ever read about deactivated/buffered sulfur additives in modern day,that is , current GL5 gear oil formulations ??

Re: GL5 MT1 in an Older Transmission [Re: redwolf4k] #4557330
10/28/17 02:39 PM
10/28/17 02:39 PM
Joined: Oct 2008
Posts: 68
NY
redwolf4k Offline OP
redwolf4k  Offline OP
Joined: Oct 2008
Posts: 68
NY
Thank you for the link, did not realize this is currently being discussed.

Seems to be two camps here, which is why I came here in the first place. If only GL4 gear oil was cheap like GL5, and not becoming exclusive to specialty brands that want $20 a quart. I do not want to support such a price point for GEAR LUBE.

Last edited by redwolf4k; 10/28/17 02:40 PM.
Re: GL5 MT1 in an Older Transmission [Re: zeng] #4557406
10/28/17 03:52 PM
10/28/17 03:52 PM
Joined: Feb 2015
Posts: 2,194
Slovenia EU
Kamele0N Offline
Kamele0N  Offline
Joined: Feb 2015
Posts: 2,194
Slovenia EU
Originally Posted By: zeng

Ever read about deactivated/buffered sulfur additives in modern day,that is , current GL5 gear oil formulations ??


Yes but that "buffered sulphur" is in yellow metal safe formulations...

And labeled as... GL4+... GL4/5...or GL5/MT-1

And NEVER under GL5....solo/alone


2011 Hyundai i30 1.4 CVVT Shell Helix Ultra 5w40
1997 Toyota Landcruiser KZJ95 3.0 TD Shell Rimula R6M 10w40
Re: GL5 MT1 in an Older Transmission [Re: Kamele0N] #4557433
10/28/17 04:25 PM
10/28/17 04:25 PM
Joined: Dec 2005
Posts: 9,861
Upper Midwest
kschachn Online content
kschachn  Online Content
Joined: Dec 2005
Posts: 9,861
Upper Midwest
Doesn't the GL-5 specification in and of itself have yellow metal protectants? My ECHO owner's manual says either is acceptable and it has brass synchronizers. I've used Mobil 1 gear oil for a long time and according to the container it is GL-5 only.


1994 BMW 530i, 228K
1996 Honda Accord, 263K
1999 Toyota Sienna, 400K
2000 Toyota ECHO, 271K
Re: GL5 MT1 in an Older Transmission [Re: redwolf4k] #4557475
10/28/17 05:18 PM
10/28/17 05:18 PM
Joined: Feb 2015
Posts: 2,194
Slovenia EU
Kamele0N Offline
Kamele0N  Offline
Joined: Feb 2015
Posts: 2,194
Slovenia EU


2011 Hyundai i30 1.4 CVVT Shell Helix Ultra 5w40
1997 Toyota Landcruiser KZJ95 3.0 TD Shell Rimula R6M 10w40
Re: GL5 MT1 in an Older Transmission [Re: redwolf4k] #4557535
10/28/17 06:25 PM
10/28/17 06:25 PM
Joined: Jun 2002
Posts: 19,229
Iowegia - USA
MolaKule Offline
MolaKule  Offline
Joined: Jun 2002
Posts: 19,229
Iowegia - USA
Originally Posted By: redwolf4k
Hello,

This may be one of the most clouded topics in regards to gear oil. In 2017, is a GL5 MT1 rated gear oil acceptable in a thirty year old brass synchro manual transmission?

GL5 gear oil is cheap nearly everywhere, GL4 gear oil is mainly from specialty brands and expensive.

I wanted to ask the pros here: GL5 MT1 = yellow metal safe?


You're missing a key point here as explained in the linked posts.

Sure GL-5 differential lubes are relatively cheap but they don't have the proper Anti-wear additive mix, nor do they have the friction modifiers that make for smooth synchro operation.

And GL-5 differential lubes have a higher viscosity than specially formulated (dedicated) MTF's, which may make shifting more of a chore in cold temps.

If your transmission requires a 75W90, then Amsoil MTG or Redline MT-90 would work a heckuvalot better in your tranny.

Last edited by MolaKule; 10/28/17 06:26 PM.

Reading is fundamental; understanding is not a given ability.
Re: GL5 MT1 in an Older Transmission [Re: Kamele0N] #4558091
10/29/17 08:02 AM
10/29/17 08:02 AM
Joined: Dec 2005
Posts: 9,861
Upper Midwest
kschachn Online content
kschachn  Online Content
Joined: Dec 2005
Posts: 9,861
Upper Midwest


1994 BMW 530i, 228K
1996 Honda Accord, 263K
1999 Toyota Sienna, 400K
2000 Toyota ECHO, 271K
Re: GL5 MT1 in an Older Transmission [Re: Kamele0N] #4558092
10/29/17 08:03 AM
10/29/17 08:03 AM
Joined: Sep 2015
Posts: 2,256
Malaysia
zeng Offline
zeng  Offline
Joined: Sep 2015
Posts: 2,256
Malaysia
Originally Posted By: Kamele0N
Originally Posted By: zeng

Ever read about deactivated/buffered sulfur additives in modern day,that is , current GL5 gear oil formulations ??


Yes but that "buffered sulphur" is in yellow metal safe formulations...

And labeled as... GL4+... GL4/5...or GL5/MT-1

And NEVER under GL5....solo/alone


Still insists GL5 corrodes yellow metal synchronizers ?
Listen to Paul's video in post #1 here from 11.25 -15.20

Edit:spelling

Last edited by zeng; 10/29/17 08:09 AM.
Re: GL5 MT1 in an Older Transmission [Re: redwolf4k] #4558323
10/29/17 11:54 AM
10/29/17 11:54 AM
Joined: Feb 2015
Posts: 2,194
Slovenia EU
Kamele0N Offline
Kamele0N  Offline
Joined: Feb 2015
Posts: 2,194
Slovenia EU
OK...it seems that you are correct...


2011 Hyundai i30 1.4 CVVT Shell Helix Ultra 5w40
1997 Toyota Landcruiser KZJ95 3.0 TD Shell Rimula R6M 10w40
Re: GL5 MT1 in an Older Transmission [Re: MolaKule] #4558984
10/30/17 06:59 AM
10/30/17 06:59 AM
Joined: Oct 2008
Posts: 68
NY
redwolf4k Offline OP
redwolf4k  Offline OP
Joined: Oct 2008
Posts: 68
NY
Originally Posted By: MolaKule
Originally Posted By: redwolf4k
Hello,

This may be one of the most clouded topics in regards to gear oil. In 2017, is a GL5 MT1 rated gear oil acceptable in a thirty year old brass synchro manual transmission?

GL5 gear oil is cheap nearly everywhere, GL4 gear oil is mainly from specialty brands and expensive.

I wanted to ask the pros here: GL5 MT1 = yellow metal safe?


You're missing a key point here as explained in the linked posts.

Sure GL-5 differential lubes are relatively cheap but they don't have the proper Anti-wear additive mix, nor do they have the friction modifiers that make for smooth synchro operation.

And GL-5 differential lubes have a higher viscosity than specially formulated (dedicated) MTF's, which may make shifting more of a chore in cold temps.

If your transmission requires a 75W90, then Amsoil MTG or Redline MT-90 would work a heckuvalot better in your tranny.


This is a good point.

What I gather from everything here is both GL4 and GL5 is safe for use, but GL4 is the fluid I should use in regards to its functionality with a manual gear box. I will do as follows: Put cheap GL5 gear oil in my Diffs and transfer case, but I will order up some Redline MT90 for the tranny, as it is something I have to feel all day long while driving. I really hate spending upwards of $20 a quart for either of these. But I guess it is only once in a while.

Thank you for all the clarification!

Last edited by redwolf4k; 10/30/17 07:04 AM.

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