Any ideas on oil for the vulnerable Honda 6 speed K series transmissions for a track/fast daily car?

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For a project where a Honda 320hp fully built k24 2.4l 4 cylinder motor is fitted to a civic we have also rebuilt the transmission with all new bearings and complete new 2nd and 3rd gear sets with synchros etc.. Also a helical diff has been fitted.

The gearbox was grinding in 2nd and 3rd gear hence why its been rebuild.
This is a common problem on these hondas, even cars that are not tracked or driven fast some gearboxes only last 100k miles.

From what i know the synchros just give out, this cause the gear to not slow down enough and because with every shift the gear is meshed in to fast in it wears down the shift bushing cassetes that go on the gear resulting in grinding etc...
This is a very notorious problem for the some times 1st, 2nd, 3rd gears on the boxes.


These transmissions a prescribed to use the Honda MTF 3 fluid, and most of the time i am a big oem fan. But i think there are better options out there to protect this rebuilt trans that will be driven hard/tracked.

As far as i know the oem honda fluid is API gl4 75w80 /5w30 motor oil.

Do any of you guys know a better option that would help the syncrhos from wearing/slowing down better and so help with the wear of the gear units?
I am also curious why that option would be better.
 
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I know for a long time now, Miata guys have been swearing by the Motorcraft special sauce XT-M5-QS as the magic elixir for some of the crunchy shifting boxes they have sometimes. Downside is, its priced like unicorn tears. Supposed to be some high grade euro made synthetic that Ford came up with to cure some of their iffy shifting trannies.

I had the "unicorn tears" in my NB1 Miata, and while the transmission performed well with it, I personally didn't notice a drastic change in its operation, for better or worse. That being said, I had a similar understanding in that it is a premium synthetic gearbox oil.
For what its worth, I currently have Motul in my FRS gearbox, and will be using Redline the next time I change it. I wish I had more relevant experiences that I could offer for the Honda gearbox.
 
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434
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Munich, Germany
Try to use a good synthetic 75w-80. I use this in my S 2000 and love it:


i have added one tube of the classic gear oil additiv from liqui Moly mixed with two liters of gear oil, this results in shifts almost as smooth as a VW gearbox: https://shop.liqui-moly.de/additive/getriebeoel-additiv.html

To protect the bearings, you may consider about adding this additive:


To my knowledge, this is a pure extreme pressure additive for geraboxes. I know that additives are a controversical topic here, but the reports about the "gear protect" are all postive. I dont use this in my S2000, but i in a gearbox of a tuned car it is worth a try to protect the bearings and gears, in my opinion. Peopel also report about smoother shifting.
 

Flyingdutchman

Thread starter
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186
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Try to use a good synthetic 75w-80. I use this in my S 2000 and love it:
Yes i think ravenol or rowe might also offer good options, i know the s2000 suffer with the same problems although those have fiber lined synchros.

The oem honda mtf-3 feels almost watery like how thin it is, maybe they have done this to help a little with the fuel consumption in their regular cars, but for their high rpm cars it doesnt seem to work.

Somebody also suggested me to got to a 75w90 instead of the oem 80.

I really think that the problem starts with the synchros not being slowed down enough. This causes the gears to grind a little, in the beginning it is not hearable but the wear is already starting then and after a certain time you can also hear it.

I spoke to someone who uses these cars for racing and said that he used something like a xxW140 gear oil, he said that with the oem oil the gearbox would only last a couple of sessions. And its not the gears that go out but the synchros. Hence why i think the oem oil is too thin.
 
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434
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Munich, Germany
The current version of Hond MTF is MTF III here, and yes, it is thin. I think Honda has gone the same route as every other automaker: Use thinner oil in the gearbox to save fuel.

Ther are some oils you can buy here in Europe that are "recomended" as Honda MTF equivalent, from Kroon Oil, Addinol, Liqui Moly, Motul, Ravenol and you can get the orignal Honda MTF, together with even more (to us europeans) exotic oils like Amsoil Syncromesh, Texaco MTF 94 and Redline. Or you could just simply use every 75w or 75w-80 GL4 oil you like.

I used the ravenol MTF II, i liked it, but it brake down fast. Within 10.000 km the shift feels "Crunchy" again.
BTW, only the facelift S2000 models has Carbon Synchro rings.

A gear oil relies on Viscositiy and / or add pack for protection. Using a thicker oil is a good idea, but i wonder how it affects shift quality. i used a a 75w-90 in a Honda del Sol gearbox many years ago and found it "undriveable". Very "Crunchy", even warm. I cant imagine how a -140 oil feels.

Thats why i came up with the idea of better Protection with added additives. I wonder what the most knowledgable person, Molakule, maybe could contribute to this topic.

Just as a note, the LM Gear protect has a blue color, Motuls best gear oil, the race prooven "Gear competition 75w-140" also has a blue color. Coincidence?

I cant recommend anything to you, i just share my thoughts. Maybe i am wrong. It will the best to ask Molakule.
 
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Redline MT-85? MT-90?
MTL would be my pick if this was a streeted car. For years, Honda said a 10W-30 motor oil was fine for their gearboxes until they were reformulated to meet CAFE/ILSAC with friction modifiers that don’t play nice with synchros or wet clutches. It was a carryover from their motorcycle arm.
 
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MTL would be my pick if this was a streeted car. For years, Honda said a 10W-30 motor oil was fine for their gearboxes until they were reformulated to meet CAFE/ILSAC with friction modifiers that don’t play nice with synchros or wet clutches. It was a carryover from their motorcycle arm.
I was looking at KV100 to see what is comparable. I know MTL is generally popular. MT-90 is popular among BMW owners, especially those that do serious track time.
 
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434
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Munich, Germany
Redline is not very populer here in Europe, because it is very expensive and a absolutely boutique oil here. It is only popular among oil lunatics. That´s why we europeans have almost zero expirience with redline gear oils. But of course, it is high quality and worth a try.
 
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12,599
Location
Colorado Springs
Redline is not very populer here in Europe, because it is very expensive and a absolutely boutique oil here. It is only popular among oil lunatics. That´s why we europeans have almost zero expirience with redline gear oils. But of course, it is high quality and worth a try.
True. One of the guys I know asked me about some oils for uphill races he does in the Balkans, and I mentioned Redline, and he was: What the hell is that?
Is this Honda in Europe? If so, I would go Motul.
 
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12,599
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Colorado Springs
The Motul line up of gear oils dont impress me, choice wise.
They recomend their "Multi DCTF", a thin 75w gear oil, for Hondas.
They are following what manufacturer says. They are not going to recommend something that manufacturer does not. They are not going into discussion which fluid does better, or whether certain failures are related to viscosity or not.
Redline and similar companies might do that. Vendors like Bimmerworld here in the US will actually tell you under which circumstances certain fluid should be used.
 

Pew

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1,367
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Illinois
Redline MTL (or the "cocktail" mix of Redline 75 and 90) and Motul 300 were the most popular non-OEM fluids for the Evo but there was no scientific data behind it; only that they were popular favorites.
 

Flyingdutchman

Thread starter
Messages
186
Location
The Netherlands
The current version of Hond MTF is MTF III here, and yes, it is thin. I think Honda has gone the same route as every other automaker: Use thinner oil in the gearbox to save fuel.

Ther are some oils you can buy here in Europe that are "recomended" as Honda MTF equivalent, from Kroon Oil, Addinol, Liqui Moly, Motul, Ravenol and you can get the orignal Honda MTF, together with even more (to us europeans) exotic oils like Amsoil Syncromesh, Texaco MTF 94 and Redline. Or you could just simply use every 75w or 75w-80 GL4 oil you like.

I used the ravenol MTF II, i liked it, but it brake down fast. Within 10.000 km the shift feels "Crunchy" again.
BTW, only the facelift S2000 models has Carbon Synchro rings.
Okay the ravenol mtf2 would look like a good option but its the same viscositiy as oem and i see it didnt help with your gearbox.

I think maybe going a 75w85 might be an option.

Its hard to come with proven soluotions for gearbox, every "group" jdm eu usa mazda honda bmw etc... have their own "wonder" oils but there isnt really any data to back it up.
Redline MTL (or the "cocktail" mix of Redline 75 and 90) and Motul 300 were the most popular non-OEM fluids for the Evo but there was no scientific data behind it; only that they were popular favorites.
Yeah i might also look into motul 300 series.

The guy that raced these hondas imported redline from the usa because he swore by it for his gearbox and going with a thicker weight.

I am still thinking honda went too thin too early because of fuel economy and thinking it could handle it.
Just like with their 0w20 oils in 2003 2004 they where one of the first to run it. (Without real problems)

Honda is known for its superb tolerances but a synchro gearbox is totaly different than a car engine.
 

Flyingdutchman

Thread starter
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186
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Ive looked into the 75w90 motul 300v.
But i stumbled on the same reason why i dont realy bother with motul any more.

Because their data sheet mentions its ester based full syntethic wonder oil

And when i look for their german canisters i see that its just hydrockracked oil in a racie style bottle for a premium price.
 

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Messages
434
Location
Munich, Germany
Its hard to come with proven soluotions for gearbox, every "group" jdm eu usa mazda honda bmw etc... have their own "wonder" oils but there isnt really any data to back it up.

You nailed it. (y)

Use a 75w-80 or 75w-90 or mix your own 75w-85 and boost it with LM gear protect or give redline a try. I think that´s all your options...
 
Messages
434
Location
Munich, Germany
Ive looked into the 75w90 motul 300v.
But i stumbled on the same reason why i dont realy bother with motul any more.

Because their data sheet mentions its ester based full syntethic wonder oil

And when i look for their german canisters i see that its just hydrockracked oil in a racie style bottle for a premium price.

Yes, me too. They even lost on court here, because they dared to sell it as "Fullysynthetic" here in germany. 🤦‍♂️

 

Flyingdutchman

Thread starter
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186
Location
The Netherlands
Use a 75w-80 or 75w-90 or mix your own 75w-85 and boost it with LM gear protect or give redline a try. I think that´s all your options...
I do not own the car where its going in but i think he will then probably use the redline MTL if we can find it for a reasonable price.
Yes, me too. They even lost on court here, because they dared to sell it as "Fullysynthetic" here in germany. 🤦‍♂️
Interesting article you shared there.
Yeah i also noticed that motul was switched to HC.
They lost me from that point.

I think in europe motul is really a marketing based supplier with no real extrordinary products.

Also the discussion on that sometimes pao based oils are a little overhyped i agree on.

I use shell in all of my personal vehicles because i believe that as one of the largest oil companies in the world they have a lot of money for r&d, they completly control their own GTL production and its their invention.

It has probably been discussed and explained over here but i dont get it why GTL can not be considered a synthetic. In my opinion it is, but hey who am i.

Shell does also offer an 75w80 gl4 gear oil and on their german website it is listed as synthetic. Maybe that also might be an option. It only has a volvo approval.
 
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434
Location
Munich, Germany
The problem with most Shell gear oils is that they are almost impossible to buy here for "Average Hans".
Most of them are only availabe in big jugs, not 1 Liter Bottles. Clearly aimed for repair shops as customers.

Shell Europe has -THE- worst Homepage of all oil companys, by the way. All datas and catalouges well hidden and no facts, only marketing Bla Bla..

Yes, our german law is a little bit dated about wich type of oil could be labeled as "fullysynthetic".

Redline is not cheap here. Reasonable? Maybe.

http://www.motorsportoel.de/

 
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