FL5/DE5 Transmission fluid reference

[AspecR]

I did not find the factory fluid to be smooth, in fact it felt like there was inconsistent and excess synchro effort.

Switching to Red Line MTL made all of that go away.

I recommend switching to Redline for anyone that asks. Felt a difference the instant I put the car in 1st gear right after the swap

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[Spart]

I recommend switching to Redline for anyone that asks. Felt a difference the instant I put the car in 1st gear right after the swap

I still can't vouch 100% for it, because I've only put about 300 miles on the car since switching, and we ran out of cold weather early. Coldest it ever got after switching was about 17°F, which it handled fine.

Assuming it holds up to more mileage and that the more extreme cold weather performance isn't awful, I would 100% recommend Red Line MTL. As it is right now, I just have no complaints about the shift feel. The synchro engagement is smooth and consistent. And yes, it was an instantaneous and obvious improvement.

 

[johnloov]

For heavy track FL5 owners, who see over 80% track time - how often are you changing your transmission fluid?

My car sees about 80% track time - it's hit 10k miles - I did my first transmission fluid change with Honda MTF at 3300 miles and I just did one at 10k miles and it smelled a bit burnt.

Does other non honda transmission fluid last longer and protect much better?

 

[Spart]

For heavy track FL5 owners, who see over 80% track time - how often are you changing your transmission fluid?

My car sees about 80% track time - it's hit 10k miles - I did my first transmission fluid change with Honda MTF at 3300 miles and I just did one at 10k miles and it smelled a bit burnt.

Does other non honda transmission fluid last longer and protect much better?

Gear oils aren't normally exposed to contaminants and so the number one enemy of their longevity is heat.

Long periods of high heat will drop the life of your gear oil exponentially as the temperature and duration rise.

If I wanted to extend my interval with heavy track use, I would 100% be installing a dedicated trans cooler and get rid of the factory heat exchanger in the process. It makes perfect sense to do so, for any fluid that you might run.

 

[johnloov]

Gear oils aren't normally exposed to contaminants and so the number one enemy of their longevity is heat.

Long periods of high heat will drop the life of your gear oil exponentially as the temperature and duration rise.

If I wanted to extend my interval with heavy track use, I would 100% be installing a dedicated trans cooler and get rid of the factory heat exchanger in the process. It makes perfect sense to do so, for any fluid that you might run.

What do you recommend stock setup for change intervals for heavy track use every six track days or every three track days and change it with my engine oil?

 

[AspecR]

For heavy track FL5 owners, who see over 80% track time - how often are you changing your transmission fluid?

My car sees about 80% track time - it's hit 10k miles - I did my first transmission fluid change with Honda MTF at 3300 miles and I just did one at 10k miles and it smelled a bit burnt.

Does other non honda transmission fluid last longer and protect much better?

Sounds like you need a transcooler and also consider moving to a higher grade transmission fluid.

 

[Spart]

What do you recommend stock setup for change intervals for heavy track use every six track days or every three track days and change it with my engine oil?

If your car is spending 80% of it's time at the track as you say, the factory setup is just inadequate.

I've only come across a few attainable cars that are truly track-ready out of the box, my old GT350 being one of them.

It's a hardware problem, not a fluid problem.

 

[johnloov]

Which higher grade transmission fluid ? And do you guys have any transmission fluid analysis ?

 

[Spart]

Which higher grade transmission fluid ? And do you guys have any transmission fluid analysis ?

Just about any quality fluid will last a long time if you can keep the temperatures down.

Forget the analysis for a minute. This is far less complicated than engine oil.

 

[AspecR]

Which higher grade transmission fluid ? And do you guys have any transmission fluid analysis ?

Do some research on GL-4/GL-4+ fluids like:

1). Redline MT-90(Currently using in my own car)
2). Castrol Syntrans Transaxle 75w-90
3). Driven STF Synchromesh
4). TRIAX Synergy Gear MT 75W-90 GL-4
5). Liqui-Moly #20012
6). Sta-Lube® API/GL-4 Multi-Purpose Gear Oil SAE 90 X1GL
7). RAVENOL TSG SAE 75W-90


DO NOT USE ANY GL-5 TRANSMISSION FLUID!

 

[Jack90210]

Gear oils aren't normally exposed to contaminants and so the number one enemy of their longevity is heat.

Long periods of high heat will drop the life of your gear oil exponentially as the temperature and duration rise.

If I wanted to extend my interval with heavy track use, I would 100% be installing a dedicated trans cooler and get rid of the factory heat exchanger in the process. It makes perfect sense to do so, for any fluid that you might run.

This is an excellent and complete answer*, and the word "exponentially" is an important one.

*One of the hats I wear at work is industrial maintenance, and the optimizing and tracking of operating temperatures to maximize lubricant life (as a means of minimizing downtime) is its own niche of applied scientific analysis.

 

[johnloov]

How often ( # of track days and miles ) are you guys changing the transmission fluid with and without a transmission cooler?

Without a transmission cooler:

every 3–4 track days, or about 2,500–4,000 miles max

With a well-designed transmission cooler and actual temp monitoring:

every 4–6 track days

Also does anyone have Blackstone reports on this?

(I've just sent my second one in and every time I change the transmission fluid MTF - feels super nice ) I really want to track hard data on this as well. I'm keeping my car close to stock as a baseline for the 2 more years under warranty and seeing what are the limits within stock form, and adjusting service intervals accordingly. So far the engine oil data is excellent, now would like to start tracking the tranmission oil analysis data also.

 

[Jack90210]

How often ( # of track days and miles ) are you guys changing the transmission fluid with and without a transmission cooler?

Without a transmission cooler:

every 3–4 track days, or about 2,500–4,000 miles max

With a well-designed transmission cooler and actual temp monitoring:

every 4–6 track days

Also does anyone have Blackstone reports on this?

(I've just sent my second one in and every time I change the transmission fluid MTF - feels super nice ) I really want to track hard data on this as well. I'm keeping my car close to stock as a baseline for the 2 more years under warranty and seeing what are the limits within stock form, and adjusting service intervals accordingly. So far the engine oil data is excellent, now would like to start tracking the tranmission oil analysis data also.

The video’s engineering claim is that current Honda MTF is the more appropriate long-term lubricant for Honda/Acura manual gearboxes because its viscosity, shear behavior, and friction characteristics are described as being tuned to Honda synchronizer geometry and materials, whereas A/C Delco Synchromesh Friction Modified was developed around a different GM synchronizer/cone design and torque/load environment. It argues that the commonly reported smoother shift feel from A/C Delco comes primarily from its higher viscosity and different friction-modifier package, which can temporarily mask wear or soften engagement, but may do so by moving the synchronizer away from the friction curve Honda intended rather than by improving true synchronization efficiency or durability. The evidence presented is comparative and inferential rather than controlled test data: a historical timeline of Honda fluid evolution, quoted viscosity/API differences, and a synchronizer-friction model, leading to the conclusion that modern Honda MTF is the higher-confidence default for healthy Honda transmissions, while A/C Delco may be best viewed as a niche or temporary workaround rather than a proven superior fluid.

This post brought back memories of filling the gearbox of my 1987 Integra with 10w30!

 

[Spart]

The video’s engineering claim is that current Honda MTF is the more appropriate long-term lubricant for Honda/Acura manual gearboxes because its viscosity, shear behavior, and friction characteristics are described as being tuned to Honda synchronizer geometry and materials, whereas A/C Delco Synchromesh Friction Modified was developed around a different GM synchronizer/cone design and torque/load environment. It argues that the commonly reported smoother shift feel from A/C Delco comes primarily from its higher viscosity and different friction-modifier package, which can temporarily mask wear or soften engagement, but may do so by moving the synchronizer away from the friction curve Honda intended rather than by improving true synchronization efficiency or durability. The evidence presented is comparative and inferential rather than controlled test data: a historical timeline of Honda fluid evolution, quoted viscosity/API differences, and a synchronizer-friction model, leading to the conclusion that modern Honda MTF is the higher-confidence default for healthy Honda transmissions, while A/C Delco may be best viewed as a niche or temporary workaround rather than a proven superior fluid.

I really wish you'd quit posting AI slop on this forum.

Like for real. It's REALLY annoying. At the bare minimum, can you please stop posting it in my thread? Keep it in your own threads.

There are two main versions of the ACDelco Synchromesh fluid, 10-4014 (in the white bottle) and 10-4006 (in the black bottle.)

Both are very good fluids. The 10-4014 is labeled as "Friction Modified" however all manual transmission fluids have at least some friction modifier additives to help the synchros work properly, and my understanding is that 10-4014 just has more than the regular blend in the black bottle.

From what I've read, 10-4014 was specifically developed to resolve problems (warranty complaints) in one specific transmission, the NV1500 installed in late 90's S10s. The complaints surrounded gear grinds early in synchro life and without abuse. Originally, these trucks specified the black bottle Synchromesh (10-4006) and GM introduced Synchromesh Friction Modified (10-4014) in an attempt to stave off warranty replacements.

Hondas have had issues with early-onset second gear grind for decades at this point, and people have repeatedly posted success stories using 10-4014.

If you are not experiencing second gear grind, I'm not sure I would automatically jump to ACDelco 10-4014. It probably won't hurt anything though. And the viscosity difference isn't that big of a deal unless you live somewhere that it gets into the double-digit negatives every winter.

 

[johnloov]

I really wish you'd quit posting AI slop on this forum.

Like for real. It's REALLY annoying. At the bare minimum, can you please stop posting it in my thread? Keep it in your own threads.

There are two main versions of the ACDelco Synchromesh fluid, 10-4014 (in the white bottle) and 10-4006 (in the black bottle.)

Both are very good fluids. The 10-4014 is labeled as "Friction Modified" however all manual transmission fluids have at least some friction modifier additives to help the synchros work properly, and my understanding is that 10-4014 just has more than the regular blend in the black bottle.

From what I've read, 10-4014 was specifically developed to resolve problems (warranty complaints) in one specific transmission, the NV1500 installed in late 90's S10s. The complaints surrounded gear grinds early in synchro life and without abuse. Originally, these trucks specified the black bottle Synchromesh (10-4006) and GM introduced Synchromesh Friction Modified (10-4014) in an attempt to stave off warranty replacements.

Hondas have had issues with early-onset second gear grind for decades at this point, and people have repeatedly posted success stories using 10-4014.

If you are not experiencing second gear grind, I'm not sure I would automatically jump to ACDelco 10-4014. It probably won't hurt anything though. And the viscosity difference isn't that big of a deal unless you live somewhere that it gets into the double-digit negatives every winter.

I simply asked:

1) What is the transmission fluid change intervals for number of track days with or without oil coolers.
2) Does anyone have Blackstone used transmission oil analysis ?

I removed the AI video summary to be respectful to you, which simply summarized the video on the Honda MTF. I do believe there seems to be an allergic reaction to anytime used engine oil analysis data is requested. We proved a lot of myths in the other thread backed by data and revalidated by experts ( like Lake Speed Jr. ). I do have friends who tracked hard their cars, much harder than me regularly at Laguna Seca that do not have oil coolers and stick with Honda MTF. I was simply asking for service intervals and data.

Please let me know if anyone has used transmission oil analysis or I can also start a new thread to collect the data and keep this thread free of Blackstone reports.

I appreciate the feedback

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