75W90 vs 75W140 transmission & diff oil
09-22-2013, 04:40 AM
#42
Registered User
I don't recommend 75w140 in a transmission. I had motul 75w140 competition on my transmission for 6 months, and it seems to damage the synchros a lot, especially 1st, 2nd and 3rd (she is DD and see tracks twice with the fluid) although I never had mis-shift or rev mis-matching.
The grinding in 2nd gear was developed a lot, and when it is cold (even after 2 min warm up), it was very hard to put into 1st or 2nd. I got redline 75w80 MTL, and situation changes a lot now. sadly, 2nd gear is still grinding sometimes, so I do double clutching. I'm considering transmission rebuild now
Most 75W140 are GL-5, and here Redline claims that "other's synthetic gear oils are often too slippery for proper synchro engagement" and "Safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage", which means 75w140 doesn't fit to transmission. As I know, a synchro needs some degree of friction, but the purpose of GL-5 oil is protecting gears so it is like cushion and very slippery, resulting that it doesn't provide what it wants.
I recommend honda MTL, or redline MTL.
BTW, I don't know the relationship between rpm and shifting gear, but when I drive in high rpm or in a track, the tranny never grinds and shifts very smoothly. maybe our tranny is designed for high rpm engine
the car is MY08, only have 40k miles on it.
To give you one tip, get an engine torque damper. Your tranny will appreciate it, and you also think that you are driving a sedan
The grinding in 2nd gear was developed a lot, and when it is cold (even after 2 min warm up), it was very hard to put into 1st or 2nd. I got redline 75w80 MTL, and situation changes a lot now. sadly, 2nd gear is still grinding sometimes, so I do double clutching. I'm considering transmission rebuild now
Most 75W140 are GL-5, and here Redline claims that "other's synthetic gear oils are often too slippery for proper synchro engagement" and "Safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage", which means 75w140 doesn't fit to transmission. As I know, a synchro needs some degree of friction, but the purpose of GL-5 oil is protecting gears so it is like cushion and very slippery, resulting that it doesn't provide what it wants.
I recommend honda MTL, or redline MTL.
BTW, I don't know the relationship between rpm and shifting gear, but when I drive in high rpm or in a track, the tranny never grinds and shifts very smoothly. maybe our tranny is designed for high rpm engine
the car is MY08, only have 40k miles on it.
To give you one tip, get an engine torque damper. Your tranny will appreciate it, and you also think that you are driving a sedan
09-22-2013, 05:21 AM
#43
I ran Amsoil MTG in my transmission at the beginning of the summer last year. MTG is a transmission specified (GL-4 - safe for yellow metals) 75W90 weight gear oil.
I'm not sure if someone else mentioned this, but a 75W90 gear oil is not significantly "thicker" than a 5W30 engine oil (not as much as the numbers may lead you to believe) - they use different reference numbers for classification. A 75W90 gear oil is close in viscosity to a 15W40 engine oil.
I have an AP2 transmission in my AP1, but I still have occasional rough 1-2 shifts when the transmission is cold - or after sitting at a light after driving on the highway for extended periods. I've also had a handful of 1-2 grinds (nowhere near as many as my AP1 transmission though). Needless to say - I've tried several things to minimize the number and severity of 1-2 grinds (GM SMFM, every version of Honda MTF, Redline MTL, Amsoil MTF). Amsoil has been the best transmission fluid I've run to date (longest lasting, lowest number of grinds etc.), but my transmission is a bit "notchier" the first couple shifts when it's below 55-60F than with other transmission fluids. Double-clutching works during that initial notchy period and then It smooths out just fine after that. I decided to try out Amsoil MTG 75W90 during the summer due to the fact my transmission breaks down fluids much faster in the summer time. I was hoping that the MTG would last longer. Here's my impressions of MTG after using the fluid for over a year (three fluid changes):
Pros:
Smoother shifting, lasts longer, far fewer grinds from 1-2 - especially when the transmission is hot.
Sounds good so far - right? Not so fast.
Con (and it's a big one for MTG in an S2000): My transmission started popping out of gear - with increasing frequency over time.
You might think the popping out of gear is due to the fact it's an '04 transmission, and that certainly may be a contributing factor. However, the popping out of gear ceased completely when I went back to Amsoil MTF (5W30 weight). Food for thought.
I'm not sure if someone else mentioned this, but a 75W90 gear oil is not significantly "thicker" than a 5W30 engine oil (not as much as the numbers may lead you to believe) - they use different reference numbers for classification. A 75W90 gear oil is close in viscosity to a 15W40 engine oil.
I have an AP2 transmission in my AP1, but I still have occasional rough 1-2 shifts when the transmission is cold - or after sitting at a light after driving on the highway for extended periods. I've also had a handful of 1-2 grinds (nowhere near as many as my AP1 transmission though). Needless to say - I've tried several things to minimize the number and severity of 1-2 grinds (GM SMFM, every version of Honda MTF, Redline MTL, Amsoil MTF). Amsoil has been the best transmission fluid I've run to date (longest lasting, lowest number of grinds etc.), but my transmission is a bit "notchier" the first couple shifts when it's below 55-60F than with other transmission fluids. Double-clutching works during that initial notchy period and then It smooths out just fine after that. I decided to try out Amsoil MTG 75W90 during the summer due to the fact my transmission breaks down fluids much faster in the summer time. I was hoping that the MTG would last longer. Here's my impressions of MTG after using the fluid for over a year (three fluid changes):
Pros:
Smoother shifting, lasts longer, far fewer grinds from 1-2 - especially when the transmission is hot.
Sounds good so far - right? Not so fast.
Con (and it's a big one for MTG in an S2000): My transmission started popping out of gear - with increasing frequency over time.
You might think the popping out of gear is due to the fact it's an '04 transmission, and that certainly may be a contributing factor. However, the popping out of gear ceased completely when I went back to Amsoil MTF (5W30 weight). Food for thought.
09-24-2013, 02:41 AM
#45
Registered User
I ran Amsoil MTG in my transmission at the beginning of the summer last year. MTG is a transmission specified (GL-4 - safe for yellow metals) 75W90 weight gear oil.
I'm not sure if someone else mentioned this, but a 75W90 gear oil is not significantly "thicker" than a 5W30 engine oil (not as much as the numbers may lead you to believe) - they use different reference numbers for classification. A 75W90 gear oil is close in viscosity to a 15W40 engine oil.
I have an AP2 transmission in my AP1, but I still have occasional rough 1-2 shifts when the transmission is cold - or after sitting at a light after driving on the highway for extended periods. I've also had a handful of 1-2 grinds (nowhere near as many as my AP1 transmission though). Needless to say - I've tried several things to minimize the number and severity of 1-2 grinds (GM SMFM, every version of Honda MTF, Redline MTL, Amsoil MTF). Amsoil has been the best transmission fluid I've run to date (longest lasting, lowest number of grinds etc.), but my transmission is a bit "notchier" the first couple shifts when it's below 55-60F than with other transmission fluids. Double-clutching works during that initial notchy period and then It smooths out just fine after that. I decided to try out Amsoil MTG 75W90 during the summer due to the fact my transmission breaks down fluids much faster in the summer time. I was hoping that the MTG would last longer. Here's my impressions after using the fluid for over a year (three fluid changes):
Pros:
Smoother shifting, lasts longer, far fewer grinds from 1-2 - especially when the transmission is hot.
Sounds good so far - right? Not so fast.
Con (and it's a big one): My transmission started popping out of gear - with increasing frequency over time.
You might think the popping out of gear is due to the fact it's an '04 transmission, and that certainly may be a contributing factor. However, the popping out of gear ceased completely when I went back to Amsoil MTF (5W30 weight). Food for thought.
I'm not sure if someone else mentioned this, but a 75W90 gear oil is not significantly "thicker" than a 5W30 engine oil (not as much as the numbers may lead you to believe) - they use different reference numbers for classification. A 75W90 gear oil is close in viscosity to a 15W40 engine oil.
I have an AP2 transmission in my AP1, but I still have occasional rough 1-2 shifts when the transmission is cold - or after sitting at a light after driving on the highway for extended periods. I've also had a handful of 1-2 grinds (nowhere near as many as my AP1 transmission though). Needless to say - I've tried several things to minimize the number and severity of 1-2 grinds (GM SMFM, every version of Honda MTF, Redline MTL, Amsoil MTF). Amsoil has been the best transmission fluid I've run to date (longest lasting, lowest number of grinds etc.), but my transmission is a bit "notchier" the first couple shifts when it's below 55-60F than with other transmission fluids. Double-clutching works during that initial notchy period and then It smooths out just fine after that. I decided to try out Amsoil MTG 75W90 during the summer due to the fact my transmission breaks down fluids much faster in the summer time. I was hoping that the MTG would last longer. Here's my impressions after using the fluid for over a year (three fluid changes):
Pros:
Smoother shifting, lasts longer, far fewer grinds from 1-2 - especially when the transmission is hot.
Sounds good so far - right? Not so fast.
Con (and it's a big one): My transmission started popping out of gear - with increasing frequency over time.
You might think the popping out of gear is due to the fact it's an '04 transmission, and that certainly may be a contributing factor. However, the popping out of gear ceased completely when I went back to Amsoil MTF (5W30 weight). Food for thought.
09-24-2013, 05:14 PM
#46
Originally Posted by slipstream444' timestamp='1379856100' post='22790483
I ran Amsoil MTG in my transmission at the beginning of the summer last year. MTG is a transmission specified (GL-4 - safe for yellow metals) 75W90 weight gear oil.
I'm not sure if someone else mentioned this, but a 75W90 gear oil is not significantly "thicker" than a 5W30 engine oil (not as much as the numbers may lead you to believe) - they use different reference numbers for classification. A 75W90 gear oil is close in viscosity to a 15W40 engine oil.
I have an AP2 transmission in my AP1, but I still have occasional rough 1-2 shifts when the transmission is cold - or after sitting at a light after driving on the highway for extended periods. I've also had a handful of 1-2 grinds (nowhere near as many as my AP1 transmission though). Needless to say - I've tried several things to minimize the number and severity of 1-2 grinds (GM SMFM, every version of Honda MTF, Redline MTL, Amsoil MTF). Amsoil has been the best transmission fluid I've run to date (longest lasting, lowest number of grinds etc.), but my transmission is a bit "notchier" the first couple shifts when it's below 55-60F than with other transmission fluids. Double-clutching works during that initial notchy period and then It smooths out just fine after that. I decided to try out Amsoil MTG 75W90 during the summer due to the fact my transmission breaks down fluids much faster in the summer time. I was hoping that the MTG would last longer. Here's my impressions after using the fluid for over a year (three fluid changes):
Pros:
Smoother shifting, lasts longer, far fewer grinds from 1-2 - especially when the transmission is hot.
Sounds good so far - right? Not so fast.
Con (and it's a big one): My transmission started popping out of gear - with increasing frequency over time.
You might think the popping out of gear is due to the fact it's an '04 transmission, and that certainly may be a contributing factor. However, the popping out of gear ceased completely when I went back to Amsoil MTF (5W30 weight). Food for thought.
I'm not sure if someone else mentioned this, but a 75W90 gear oil is not significantly "thicker" than a 5W30 engine oil (not as much as the numbers may lead you to believe) - they use different reference numbers for classification. A 75W90 gear oil is close in viscosity to a 15W40 engine oil.
I have an AP2 transmission in my AP1, but I still have occasional rough 1-2 shifts when the transmission is cold - or after sitting at a light after driving on the highway for extended periods. I've also had a handful of 1-2 grinds (nowhere near as many as my AP1 transmission though). Needless to say - I've tried several things to minimize the number and severity of 1-2 grinds (GM SMFM, every version of Honda MTF, Redline MTL, Amsoil MTF). Amsoil has been the best transmission fluid I've run to date (longest lasting, lowest number of grinds etc.), but my transmission is a bit "notchier" the first couple shifts when it's below 55-60F than with other transmission fluids. Double-clutching works during that initial notchy period and then It smooths out just fine after that. I decided to try out Amsoil MTG 75W90 during the summer due to the fact my transmission breaks down fluids much faster in the summer time. I was hoping that the MTG would last longer. Here's my impressions after using the fluid for over a year (three fluid changes):
Pros:
Smoother shifting, lasts longer, far fewer grinds from 1-2 - especially when the transmission is hot.
Sounds good so far - right? Not so fast.
Con (and it's a big one): My transmission started popping out of gear - with increasing frequency over time.
You might think the popping out of gear is due to the fact it's an '04 transmission, and that certainly may be a contributing factor. However, the popping out of gear ceased completely when I went back to Amsoil MTF (5W30 weight). Food for thought.
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