GL-4/GL-5 gear oils a compromise?
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Originally Posted by Bill_W
Been shopping for an alternative to the OEM 75w-90 GL-4 gear oil for my 2019 Miata MT. Aftermarket gear oil has some GL-4 and GL-5 combo in that weight. Am I better off looking at just the GL-4 75w-90 gear oil?
ABSOLUTELY!
Your car would do fine with a 75w-80 fluid as well as long as it is a GL-4 fluid only. DO NOT USE A SYNCHROMESH fluid either many are only rated GL-3.
The Miata specifies GL-4 ONLY.... The difference between the specs is significant enough that even a compromise fluid that says GL-4+, GL-4/5, ect will not give the smooth shifting synchro performance that you want and that the OEM designed in. Stick with GL-4 ONLY plenty of fluids to choose from the only thing being you'll probably need to order from online unless you have a European/Japanese parts or performance shop nearby.
An alternative is a Japanese/European motorcycle shop or dealership....they will have dedicated GL-4 fluids more than likely.
Been shopping for an alternative to the OEM 75w-90 GL-4 gear oil for my 2019 Miata MT. Aftermarket gear oil has some GL-4 and GL-5 combo in that weight. Am I better off looking at just the GL-4 75w-90 gear oil?
ABSOLUTELY!
Your car would do fine with a 75w-80 fluid as well as long as it is a GL-4 fluid only. DO NOT USE A SYNCHROMESH fluid either many are only rated GL-3.
The Miata specifies GL-4 ONLY.... The difference between the specs is significant enough that even a compromise fluid that says GL-4+, GL-4/5, ect will not give the smooth shifting synchro performance that you want and that the OEM designed in. Stick with GL-4 ONLY plenty of fluids to choose from the only thing being you'll probably need to order from online unless you have a European/Japanese parts or performance shop nearby.
An alternative is a Japanese/European motorcycle shop or dealership....they will have dedicated GL-4 fluids more than likely.
Biggest prb with a higher than GL-4 rating is damage to the yellow metals synchro rings. And the GL-3 product doesn't protect against wear enuf. Just use GL-4. In spec'ing 75W-90 Mazda is trying to give it some better wear protection perhaps at a cost of some cold start-up shift smoothness. Try to find the lowest viscosity you can within this SAE grade. It's quite a range.
Try this "white paper" https://www.bobistheoilguy.com/foru...nual-transmission-lubricants#Post5144795
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Ignore the API rating, find a specific manual tranmission oil with a viscosity to suit your usage and ambient conditions. Molakule has a list around here somewhere.
I personally don't like oils that are rated both GL-4 and GL-5, or rather don't trust them.
In manual transmissions with brass syncros, GL-4 is the only way to go.
In manual transmissions with brass syncros, GL-4 is the only way to go.
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Originally Posted by FordCapriDriver
I personally don't like oils that are rated both GL-4 and GL-5, or rather don't trust them.
In manual transmissions with brass syncros, GL-4 is the only way to go.
Reminds me of what we call a Fish & Ski boat … feels like a compromise happened
I know some GL5 print big & bold not for GL4 applications
Have used Redline in the transfer case but Delvac 1 in the pumpkins … it's all good value then
I personally don't like oils that are rated both GL-4 and GL-5, or rather don't trust them.
In manual transmissions with brass syncros, GL-4 is the only way to go.
Reminds me of what we call a Fish & Ski boat … feels like a compromise happened
I know some GL5 print big & bold not for GL4 applications
Have used Redline in the transfer case but Delvac 1 in the pumpkins … it's all good value then
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GL5 gear lubes also have additives that will make the gears crunch when you shift if used in a GL4 only spec tranny. GL4's have the proper add pack for shiftability.
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And seems many that are meant to take shocks are GL5 …
Being they have their own housings … and these products are sold in quarts or gallons … I'd be buying both if that's what I needed … not like you service driveline kit that often anyway …
Being they have their own housings … and these products are sold in quarts or gallons … I'd be buying both if that's what I needed … not like you service driveline kit that often anyway …
From what I can work out, GL-5/GL-4 lubes are GL-5 lubes with selected additives that don't hurt brass components.
The lubes I don't understand are the likes of Fuchs Sintopoid 75w80 which is strictly an MTF but has API GL-5 rating, or even the Ford 'Honey' designed for MTX75 gearboxes.
The lubes I don't understand are the likes of Fuchs Sintopoid 75w80 which is strictly an MTF but has API GL-5 rating, or even the Ford 'Honey' designed for MTX75 gearboxes.
Originally Posted by aquariuscsm
GL5 gear lubes also have additives that will make the gears crunch when you shift if used in a GL4 only spec tranny. GL4's have the proper add pack for shiftability.
++1
GL5 gear lubes also have additives that will make the gears crunch when you shift if used in a GL4 only spec tranny. GL4's have the proper add pack for shiftability.
++1
https://www.bobistheoilguy.com/foru...0f-need-help-choosing-mt-oil#Post5282140
If you can not find a GL4 fluid (what I read here you have problems with availability over the pond)...search for OEM approvals wich has GL4 only...
Like VW 501.50......or similar from BMW or MB or....younameit......whatever it is easier to get in your area (wich dealer you have nearbly)
If you can not find a GL4 fluid (what I read here you have problems with availability over the pond)...search for OEM approvals wich has GL4 only...
Like VW 501.50......or similar from BMW or MB or....younameit......whatever it is easier to get in your area (wich dealer you have nearbly)
There is some debate on fluids for the most recent generations of MX-5.
Yes, Mazda recommends GL-4 fluid in the transmission. However some of us use GL-4/GL-5 recommended fluid for better protection/performance, specifically the Motul Gear 300, and a lot of others think we're wrong. I am of the opinion that the quality of the fluid means more than rating.
I used 75W90 Motul Gear 300 in my 2010 MX-5, which also called for GL-4, for 120K and 8 years without any issues other than a slight difficult 1-2 shift on cold mornings until the transmission came up to temperature. When I changed it the fluid coming out looked as good as the new fluid going in. This was in a modified car that saw a lot of hard track and autocross use without a single issue.
The Gear 300 is a GL-4/GL-5 rated fluid.
https://d23zpyj32c5wn3.cloudfront.n...106/Gear_20300_2075W90_GB.pdf?1492016023
Some of you may not know but the 2016+ MX-5 transmission hasn't proven to be the most reliable. Especially when used in autocross or track use. I now have a 2019 MX-5 and am concerned about the reliability of the transmission especially it is modified and will see autocross and track use.
As you probably know the MX-5 is a very popular car to use in motorsports. As such they have seen a lot of transmission issues. The MX-5 Cup Cars have switched to an aftermarket sequential transmission to solve their issues. The rest of us aren't so lucky.
Walter Motorsport, an MX-5 race shop has had several of these transmissions apart and has documented what they call a "fundamentally flawed transmission with cheap bearings and poor tolerances." They also state that the factory fluid should not be used as it is the wrong formulation.
They are recommending either the Motul Gear Competition 75W140 or the Lucas Oil 75W140.
https://d23zpyj32c5wn3.cloudfront.n...20Competition_2075W140_GB.pdf?1492016023
https://lucasoil.com/pdf/TDS_SAE-75W-140-GO.pdf
So while I understand that for the majority of seniors who Sunday cruise their MX-5's the best recommendation is to use the recommended GL-4 oil. Most people use the Motorcraft GL-4.
However, there are those of us that need better fluid and make our own decisions about what to use and that starts with a quality fluid over a rating.
Yes, Mazda recommends GL-4 fluid in the transmission. However some of us use GL-4/GL-5 recommended fluid for better protection/performance, specifically the Motul Gear 300, and a lot of others think we're wrong. I am of the opinion that the quality of the fluid means more than rating.
I used 75W90 Motul Gear 300 in my 2010 MX-5, which also called for GL-4, for 120K and 8 years without any issues other than a slight difficult 1-2 shift on cold mornings until the transmission came up to temperature. When I changed it the fluid coming out looked as good as the new fluid going in. This was in a modified car that saw a lot of hard track and autocross use without a single issue.
The Gear 300 is a GL-4/GL-5 rated fluid.
https://d23zpyj32c5wn3.cloudfront.n...106/Gear_20300_2075W90_GB.pdf?1492016023
Some of you may not know but the 2016+ MX-5 transmission hasn't proven to be the most reliable. Especially when used in autocross or track use. I now have a 2019 MX-5 and am concerned about the reliability of the transmission especially it is modified and will see autocross and track use.
As you probably know the MX-5 is a very popular car to use in motorsports. As such they have seen a lot of transmission issues. The MX-5 Cup Cars have switched to an aftermarket sequential transmission to solve their issues. The rest of us aren't so lucky.
Walter Motorsport, an MX-5 race shop has had several of these transmissions apart and has documented what they call a "fundamentally flawed transmission with cheap bearings and poor tolerances." They also state that the factory fluid should not be used as it is the wrong formulation.
They are recommending either the Motul Gear Competition 75W140 or the Lucas Oil 75W140.
https://d23zpyj32c5wn3.cloudfront.n...20Competition_2075W140_GB.pdf?1492016023
https://lucasoil.com/pdf/TDS_SAE-75W-140-GO.pdf
So while I understand that for the majority of seniors who Sunday cruise their MX-5's the best recommendation is to use the recommended GL-4 oil. Most people use the Motorcraft GL-4.
However, there are those of us that need better fluid and make our own decisions about what to use and that starts with a quality fluid over a rating.
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.
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.
You don't understand trying to improve the performance over what the factory uses? Their goal is for the car to make it the end of the warranty period without costing them anything. That's it.
When I drain the fluid in my car's transmission next month, I'm going to have an oil analysis done.
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.
You don't understand trying to improve the performance over what the factory uses? Their goal is for the car to make it the end of the warranty period without costing them anything. That's it.
When I drain the fluid in my car's transmission next month, I'm going to have an oil analysis done.
MolaKule
Staff member
Originally Posted by Bill_W
Been shopping for an alternative to the OEM 75w-90 GL-4 gear oil for my 2019 Miata MT. Aftermarket gear oil has some GL-4 and GL-5 combo in that weight. Am I better off looking at just the GL-4 75w-90 gear oil?
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
Been shopping for an alternative to the OEM 75w-90 GL-4 gear oil for my 2019 Miata MT. Aftermarket gear oil has some GL-4 and GL-5 combo in that weight. Am I better off looking at just the GL-4 75w-90 gear oil?
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
