GL-4/GL-5 gear oils a compromise?
- Thread starter Bill_W
- Start date
Originally Posted by Farnsworth
On a 2019 Miata I would think it doesn't need changing or if someone wants to flush wear particles away they would buy correct Mazda oil from a dealer. Car cost some money I just don't understand trying to fix it from the state it was as delivered. They do a lot of testing and have extensive knowledge about lubricants when they produced the car to sell.
Wise advise... and honestly the Miata crowds are really heavy on aftermarket. In the transmission Gear oil is not immune to the aftermarket bug. One place where OEM is the best choice.
On a 2019 Miata I would think it doesn't need changing or if someone wants to flush wear particles away they would buy correct Mazda oil from a dealer. Car cost some money I just don't understand trying to fix it from the state it was as delivered. They do a lot of testing and have extensive knowledge about lubricants when they produced the car to sell.
Wise advise... and honestly the Miata crowds are really heavy on aftermarket. In the transmission Gear oil is not immune to the aftermarket bug. One place where OEM is the best choice.
Originally Posted by MolaKule
If this is for your manual transmission here is a list of MTF oils with GL-4 ratings in the 75W90 grade:
1. Amsoil MTGÂ
2. Redline MT-90Â
3. Castrol Syntrans Multivehicle 75W-90
4. Castrol Syntrans Transaxle 75w-90
5. Ford XT-75W90-QGT
6. Ford MOTORCRAFT® Full Synthetic Manual Transmission Fluid XT-M5-QSÂ
7. ACDelco 10-4059 GL-4 75W-90 Manual Transmission Fluid
8. RAVENOL TSG SAE 75W-90
9. LiquiMoly 75W-90 GL4
10. Pennzoil 75W90 GL-4
That's it? Nothing about the science/engineering/chemistry behind fluids that are rated both GL-4 and GL-5?
Specifically in response to this post above:
Originally Posted by Shannow
Molakule has a statement somewhere that you can't actually do both GL4/5...find a GL4.
If this is for your manual transmission here is a list of MTF oils with GL-4 ratings in the 75W90 grade:
1. Amsoil MTGÂ
2. Redline MT-90Â
3. Castrol Syntrans Multivehicle 75W-90
4. Castrol Syntrans Transaxle 75w-90
5. Ford XT-75W90-QGT
6. Ford MOTORCRAFT® Full Synthetic Manual Transmission Fluid XT-M5-QSÂ
7. ACDelco 10-4059 GL-4 75W-90 Manual Transmission Fluid
8. RAVENOL TSG SAE 75W-90
9. LiquiMoly 75W-90 GL4
10. Pennzoil 75W90 GL-4
That's it? Nothing about the science/engineering/chemistry behind fluids that are rated both GL-4 and GL-5?
Specifically in response to this post above:
Originally Posted by Shannow
Molakule has a statement somewhere that you can't actually do both GL4/5...find a GL4.
MolaKule
Staff member
Originally Posted by sjd
Originally Posted by MolaKule
If this is for your manual transmission here is a list of MTF oils with GL-4 ratings in the 75W90 grade:
1. Amsoil MTGÂ
2. Redline MT-90Â
3. Castrol Syntrans Multivehicle 75W-90
4. Castrol Syntrans Transaxle 75w-90
5. Ford XT-75W90-QGT
6. Ford MOTORCRAFT® Full Synthetic Manual Transmission Fluid XT-M5-QSÂ
7. ACDelco 10-4059 GL-4 75W-90 Manual Transmission Fluid
8. RAVENOL TSG SAE 75W-90
9. LiquiMoly 75W-90 GL4
10. Pennzoil 75W90 GL-4
That's it? Nothing about the science/engineering/chemistry behind fluids that are rated both GL-4 and GL-5?
Specifically in response to this post above:
Originally Posted by Shannow
Molakule has a statement somewhere that you can't actually do both GL4/5...find a GL4.
What specific technical information are you looking for?
Originally Posted by MolaKule
If this is for your manual transmission here is a list of MTF oils with GL-4 ratings in the 75W90 grade:
1. Amsoil MTGÂ
2. Redline MT-90Â
3. Castrol Syntrans Multivehicle 75W-90
4. Castrol Syntrans Transaxle 75w-90
5. Ford XT-75W90-QGT
6. Ford MOTORCRAFT® Full Synthetic Manual Transmission Fluid XT-M5-QSÂ
7. ACDelco 10-4059 GL-4 75W-90 Manual Transmission Fluid
8. RAVENOL TSG SAE 75W-90
9. LiquiMoly 75W-90 GL4
10. Pennzoil 75W90 GL-4
That's it? Nothing about the science/engineering/chemistry behind fluids that are rated both GL-4 and GL-5?
Specifically in response to this post above:
Originally Posted by Shannow
Molakule has a statement somewhere that you can't actually do both GL4/5...find a GL4.
What specific technical information are you looking for?
A fantastic thread on here explaining GL-4 and GL-5 with some excellent information from Bob.
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/501240/1
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/501240/1
Originally Posted by MolaKule
What specific technical information are you looking for?
The statement that you "can't do a GL-4/5" or whatever that means.
As I posted above, I have run a GL-4/GL-5 oil in a transmission that recommend GL-4 and am taking heat for it from people with no science to back it up just claims of "that's not what Mazda recommends." If you have that science I'd like to hear why. The thread I just posted above some excellent points as to why I can run a GL-4/GL-5 fluid in my transmission that recommends GL-4.
What specific technical information are you looking for?
The statement that you "can't do a GL-4/5" or whatever that means.
As I posted above, I have run a GL-4/GL-5 oil in a transmission that recommend GL-4 and am taking heat for it from people with no science to back it up just claims of "that's not what Mazda recommends." If you have that science I'd like to hear why. The thread I just posted above some excellent points as to why I can run a GL-4/GL-5 fluid in my transmission that recommends GL-4.
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If you look at GL-4 and GL-5 you can see it goes way back. The GL-4 has some very modern formulations which means improvements in the package. We all have our reasons to choose our fluid. Personally I like a modern formulation of what Mazda has asked for for my 2019 Miata. (GL-4 75w-90) As of yet my choice is OEM, but still on the lookout. By the way I am 66 years old.
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Originally Posted by Bill_W
If you look at GL-4 and GL-5 you can see it goes way back. The GL-4 has some very modern formulations which means improvements in the package. We all have our reasons to choose our fluid. Personally I like a modern formulation of what Mazda has asked for for my 2019 Miata. (GL-4 75w-90) As of yet my choice is OEM, but still on the lookout. By the way I am 66 years old.
So you recognize that GL-4 has some very modern formulations to improve it but don't accept that GL-4/GL-5 rated oils also have modern formulations that allow them to be run in an application that requires GL-4?
We do have our reasons for running the fluid we do and I don't fault anyone who uses the OEM oil but I certainly do get faulted for my choice not to.
If you look at GL-4 and GL-5 you can see it goes way back. The GL-4 has some very modern formulations which means improvements in the package. We all have our reasons to choose our fluid. Personally I like a modern formulation of what Mazda has asked for for my 2019 Miata. (GL-4 75w-90) As of yet my choice is OEM, but still on the lookout. By the way I am 66 years old.
So you recognize that GL-4 has some very modern formulations to improve it but don't accept that GL-4/GL-5 rated oils also have modern formulations that allow them to be run in an application that requires GL-4?
We do have our reasons for running the fluid we do and I don't fault anyone who uses the OEM oil but I certainly do get faulted for my choice not to.
To my limited knowledge-the only time I would run a dual rated gear oil for transmission is when they both house the same fluid-otherwise would use a gl4 fluid. Reason I think this is it seems the gl4 fluids focus on using a plethora of anti wear additives-for example have seen Redline MTL has tons of calcium and other anti wear additives with suitable friction coefficient for transmission gears. A dual rated gear oil never has the amount of detectable anti-wear additives.
To me the more interesting question is whether a singular Gl-5 fluid is superior to a dual rated gl4/gl5 fluid in the rear differential. Have asked this before and remember MolaKuke mentioning that the dual rated fluids add extra anti-wear properties-otherwise not needed for the rear differential. I often wonder what does the anti-wear portion of the gear oil do jn the differential and does it have any even minimal impact on the extreme pressure additives needed for Gl-5 fluid.
To me the more interesting question is whether a singular Gl-5 fluid is superior to a dual rated gl4/gl5 fluid in the rear differential. Have asked this before and remember MolaKuke mentioning that the dual rated fluids add extra anti-wear properties-otherwise not needed for the rear differential. I often wonder what does the anti-wear portion of the gear oil do jn the differential and does it have any even minimal impact on the extreme pressure additives needed for Gl-5 fluid.
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I had Motul Motylgear 75w90 wich was GL4/5 in a LC transmission...and it didnt shift good...especially when cold
R150f transmission is approved for either Gl4 or GL5....but for me it works Best with Gl4...
R150f transmission is approved for either Gl4 or GL5....but for me it works Best with Gl4...
MolaKule
Staff member
Originally Posted by sjd
Originally Posted by MolaKule
What specific technical information are you looking for?
The statement that you "can't do a GL-4/5" or whatever that means.
As I posted above, I have run a GL-4/GL-5 oil in a transmission that recommend GL-4 and am taking heat for it from people with no science to back it up just claims of "that's not what Mazda recommends." If you have that science I'd like to hear why. The thread I just posted above some excellent points as to why I can run a GL-4/GL-5 fluid in my transmission that recommends GL-4.
I am not sure what Shannow had in mind since he didn't post a link regarding his statement.
What specific brand of fluid and viscosity are you running and for what vehicle?
Now Subaru had an "S" version of their transaxle fluid which had a common sump for the transmission and the hypoid differential and it was rated GL-5, which meant it had the proper friction modification for the synchro assembly and enough AW chemistry for the differential.
Most modern MT's and transaxles only need a GL-4 rated fluid since the internal loads and gearing type only require that level of wear protection.
My response to the OP, Bill_W, was to replace his fluid from one of from the list of GL-4 fluids I gave in post #5385343.
For more technical information I have an updated White Paper here:
Manual Transmissions and Lubricants
Originally Posted by MolaKule
What specific technical information are you looking for?
The statement that you "can't do a GL-4/5" or whatever that means.
As I posted above, I have run a GL-4/GL-5 oil in a transmission that recommend GL-4 and am taking heat for it from people with no science to back it up just claims of "that's not what Mazda recommends." If you have that science I'd like to hear why. The thread I just posted above some excellent points as to why I can run a GL-4/GL-5 fluid in my transmission that recommends GL-4.
I am not sure what Shannow had in mind since he didn't post a link regarding his statement.
What specific brand of fluid and viscosity are you running and for what vehicle?
Now Subaru had an "S" version of their transaxle fluid which had a common sump for the transmission and the hypoid differential and it was rated GL-5, which meant it had the proper friction modification for the synchro assembly and enough AW chemistry for the differential.
Most modern MT's and transaxles only need a GL-4 rated fluid since the internal loads and gearing type only require that level of wear protection.
My response to the OP, Bill_W, was to replace his fluid from one of from the list of GL-4 fluids I gave in post #5385343.
For more technical information I have an updated White Paper here:
Manual Transmissions and Lubricants
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Originally Posted by MolaKule
I am not sure what Shannow had in mind since he didn't post a link regarding his statement.
What specific brand of fluid and viscosity are you running and for what vehicle?
Now Subaru had an "S" version of their transaxle fluid which had a common sump for the transmission and the hypoid differential and it was rated GL-5, which meant it had the proper friction modification for the synchro assembly and enough AW chemistry for the differential.
Most modern MT's and transaxles only need a GL-4 rated fluid since the internal loads and gearing type only require that level of wear protection.
My response to the OP, Bill_W, was to replace his fluid from one of from the list of GL-4 fluids I gave in post #5385343.
For more technical information I have an updated White Paper here:
Manual Transmissions and Lubricants
Thank you for the reply.
I have a 2019 MX-5 and plan to run either the Motul Gear 300 75W90 or Motul Competition 75W140. The 75W90 is a GL-4/GL-5 rated fluid while the 75W140 is a GL-5.
As I mentioned above, these transmissions haven't been the most reliable and an MX-5 transmission builder/motorsports shop is recommending the 75W140 for track and autocross use.
I am not sure what Shannow had in mind since he didn't post a link regarding his statement.
What specific brand of fluid and viscosity are you running and for what vehicle?
Now Subaru had an "S" version of their transaxle fluid which had a common sump for the transmission and the hypoid differential and it was rated GL-5, which meant it had the proper friction modification for the synchro assembly and enough AW chemistry for the differential.
Most modern MT's and transaxles only need a GL-4 rated fluid since the internal loads and gearing type only require that level of wear protection.
My response to the OP, Bill_W, was to replace his fluid from one of from the list of GL-4 fluids I gave in post #5385343.
For more technical information I have an updated White Paper here:
Manual Transmissions and Lubricants
Thank you for the reply.
I have a 2019 MX-5 and plan to run either the Motul Gear 300 75W90 or Motul Competition 75W140. The 75W90 is a GL-4/GL-5 rated fluid while the 75W140 is a GL-5.
As I mentioned above, these transmissions haven't been the most reliable and an MX-5 transmission builder/motorsports shop is recommending the 75W140 for track and autocross use.
Originally Posted by Bill_W
Wondered if this view can help?
https://www.widman.biz/uploads/Transaxle_oil.pdf
So you're posting something from a Corvair enthusiast? Those are 60 year transmissions. What are his credentials?
My point is that the actual quality of the oil makes the difference and you can't say all GL-5 oils are the same just because they meet the same standard. You can't seem to wrap your head around this at all. All GL-5 oils are NOT created equal. Why do you think Motul would say it can be used in a GL-4 transmission if it couldn't?
Wondered if this view can help?
https://www.widman.biz/uploads/Transaxle_oil.pdf
So you're posting something from a Corvair enthusiast? Those are 60 year transmissions. What are his credentials?
My point is that the actual quality of the oil makes the difference and you can't say all GL-5 oils are the same just because they meet the same standard. You can't seem to wrap your head around this at all. All GL-5 oils are NOT created equal. Why do you think Motul would say it can be used in a GL-4 transmission if it couldn't?
I found some more information from MolaKule. Not sure why these posts aren't stickied as they answer a lot of common questions here. Some fantastic takeaways about dual rated GL-4/GL-5 fluids. His words are italicized.
GL-4; Specified for hypoid gear service under severe service but without shock loading. This classification is essentially obsolete but is still specified by some manual transmission/transaxle manufacturers.
GL-4 is obsolete. Full stop.
"It is this author's opinion that the API needs to get off their "duff" and reclassify gear lubes according to the intended application(s), and to also recognize the differences between the old mineral-bases fluids and the new synthetic fluids."
So the quality of the oil matters? Who would have thought that?
"And let me state this for the nth time, modern GL5 lubricant formulations are safe in most components/units. When there is a mismatch, it is usually a mismatch between viscosity and friction modification."
This should be in bold at the top of this section of the forum. The key is modern GL-5 lubricant formulations.
"GL5 dual rated products simply means that it is supposed to be backward compatible and that the GL5 Z-S-P add pack is more than sufficient for GL4. The problem is, the GL5 usually contains thickeners and tackifiers that might make shifting more difficult in cold weather for a purely rated GL4. In my view, only a full synthetic, properly formulated GL5 could have a dual rating."
So a full synthetic, properly formulated like both Motul fluids I posted above?
Motul's information on their dual rated 75W90 Gear 300. Sounds like it works in just about any transmission, transaxle or differential.
"100% synthetic lubricant for all mechanical transmission of high performances and racing cars. For synchronised or not synchronised gearboxes, gearbox/differential, transfer gearboxes and hypoid differentials without limited slip system operating under shocks, heavy loads and low revolution speed or moderate loads and high revolution speed. 0% shear loss: Unshearable oil film in extreme conditions. Very high lubricating power which decreases friction and wear. 90 grade at hot temperature to provide outstanding oil film resistance at hot temperature and/or to reduce transmission noise. Fluid at low temperature to allow comfortable gear shifting."
Both threads that I took MolaKule quotes from are here:
https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=729255
https://www.bobistheoilguy.com/foru...ear_Tribology_and_Lubrication#Post729289
GL-4; Specified for hypoid gear service under severe service but without shock loading. This classification is essentially obsolete but is still specified by some manual transmission/transaxle manufacturers.
GL-4 is obsolete. Full stop.
"It is this author's opinion that the API needs to get off their "duff" and reclassify gear lubes according to the intended application(s), and to also recognize the differences between the old mineral-bases fluids and the new synthetic fluids."
So the quality of the oil matters? Who would have thought that?
"And let me state this for the nth time, modern GL5 lubricant formulations are safe in most components/units. When there is a mismatch, it is usually a mismatch between viscosity and friction modification."
This should be in bold at the top of this section of the forum. The key is modern GL-5 lubricant formulations.
"GL5 dual rated products simply means that it is supposed to be backward compatible and that the GL5 Z-S-P add pack is more than sufficient for GL4. The problem is, the GL5 usually contains thickeners and tackifiers that might make shifting more difficult in cold weather for a purely rated GL4. In my view, only a full synthetic, properly formulated GL5 could have a dual rating."
So a full synthetic, properly formulated like both Motul fluids I posted above?
Motul's information on their dual rated 75W90 Gear 300. Sounds like it works in just about any transmission, transaxle or differential.
"100% synthetic lubricant for all mechanical transmission of high performances and racing cars. For synchronised or not synchronised gearboxes, gearbox/differential, transfer gearboxes and hypoid differentials without limited slip system operating under shocks, heavy loads and low revolution speed or moderate loads and high revolution speed. 0% shear loss: Unshearable oil film in extreme conditions. Very high lubricating power which decreases friction and wear. 90 grade at hot temperature to provide outstanding oil film resistance at hot temperature and/or to reduce transmission noise. Fluid at low temperature to allow comfortable gear shifting."
Both threads that I took MolaKule quotes from are here:
https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=729255
https://www.bobistheoilguy.com/foru...ear_Tribology_and_Lubrication#Post729289
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I'm unaware of any GL-5 MTFs. Motul gear 300 is edging on saying it's designed for MTs with "For synchronised or not synchronised gearboxes..." but that isn't communication to me that it has the correct friction modification to assist (/for) synchros.
Subaru used to make a GL-5 MTF, but their newest fluid is believed to just be "plain" GL-5.
Subaru manual transmission owners are still hungry. Mola, we need your help.
Subaru used to make a GL-5 MTF, but their newest fluid is believed to just be "plain" GL-5.
Subaru manual transmission owners are still hungry. Mola, we need your help.
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Originally Posted by Brian553
I'm unaware of any GL-5 MTFs. Motul gear 300 is edging on saying it's designed for MTs with "For synchronised or not synchronised gearboxes..." but that isn't communication to me that it has the correct friction modification to assist (/for) synchros.
Subaru used to make a GL-5 MTF, but their newest fluid is believed to just be "plain" GL-5.
Subaru manual transmission owners are still hungry. Mola, we need your help.
There's actually quite a few.
Fords 'Honey' for the MTX75 is a 75w90 MTF that meets API GL-5. And then there's also Fuchs Sintopoid 75w80.
I think I would be happy using an MTF which meets GL-5 in a transfer box or differential.
I'm unaware of any GL-5 MTFs. Motul gear 300 is edging on saying it's designed for MTs with "For synchronised or not synchronised gearboxes..." but that isn't communication to me that it has the correct friction modification to assist (/for) synchros.
Subaru used to make a GL-5 MTF, but their newest fluid is believed to just be "plain" GL-5.
Subaru manual transmission owners are still hungry. Mola, we need your help.
There's actually quite a few.
Fords 'Honey' for the MTX75 is a 75w90 MTF that meets API GL-5. And then there's also Fuchs Sintopoid 75w80.
I think I would be happy using an MTF which meets GL-5 in a transfer box or differential.
