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

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.
Yeah most of the time their products are only available in 1l canisters or 209liters or something. I always buy multiple 1l canisters because luckily shell is always very cheap.

The second link you send has the cheapest redline mtl in the EU that i have seen so far so i will look into that.

I agree that their marketing is more focused on the average consumer. And their lubematch is also not very accurate some times.
However in my personal vehichles/motorcycles shell performed with the best results as far as i can personally observe. And most of the times its also the cheapest.
What i also like is that their specifications/approvals are always real certifiied.
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've noticed more grassroot track guys here prefer Motul while the "fast street guys" prefer Redline. Again no scientific data but Redline seems to be more accessible than Motul, although you'd still have to go to the specialty shops to buy them. I wish I tried out 300 over MTL for the final drain/fill for the Evo but I'm sure I'd come out with the same results for both.
I’ve never had a built Honda but I have Pennzoil synchromesh in my accord and used it before in others with success. My top choice in manual trans oil is always redline but since this is available locally and relatively cheap, it’s what I use.
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.
Maxlife ATF with lubegard red.
Your trans will be as happy as a pig in ....................
Happy Holidays.
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:

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.
The LiquidMoly additive says "For manual and differential gears, axle drives without an integrated differential lock running in the oil as well as mechanical steering systems, especially with high thermal loads."

You don't need an EP additive in a manual transmission. EP additives are for differentials regardless of LiquidMoly's marketing. An EP additive does nothing in terms of Friction Modification.

With the type of gearing used in manual transmission, anti-wear chemistry, not EP chemistry, should be used. Anti-wear and friction modification chemistry is already included in dedicated (application specific) MTF DI additive packages.

If you are racing or using modified engines with greater horsepower, use a dedicated MTF and go up one notch in the 100C viscosity spec.
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.
A 50/50 mix of Redline D4ATF and Redline MTL is a popular manual transmission mix for BMWs.