Be all End all 6MT transmission fluid thread

[504]

hi all,

so after seeing all these transmission fluid threads scattered all over the forum with no real direction, I feel it would be quite beneficial to have this thread started with the primary aim to be objective as possible in this very subjective topic.

As we all know, the performance of transmission fluids are generally based off of feel. Climate, the driver and even manufacturing variations are all variables we cannot control to provide accurate deductions but we do have the ability to create a large pool of opinion to make a much more informed decision on your next choice of fluid.


I will start with my personal experience so far and create a basic template which I am open to expand on if you guys like so here goes.


Choice of fluid: Stock Fluid
Miles on oil: 8000
Climate: 10c to 45c
experience: Fluid performed perfectly. The only issue to note was a second gear lockout on the very first shift of the day and perhaps a 5th to 4th catch occasionally. Even with the lockout it was never a crunchy experience. Fluid took about 8 minutes or so to warm up. Once drained the fluid came out somewhat clean, no real worrying visible signs

UOA: not available



Choice of fluid: Redline MTL
Miles on oil: 2000
Climate: 10c to 45c
experience: This fluid never locked me out but had a crunchy feel getting into second the first couple of shifts. Once warm, 2nd gear would still have a slight crunch which is quite irritating. the transmission would make an audible clank sound; almost as though the fluid is too slippery. I then drained 1L and added Redline MT90 in hopes to cure it. It has reduced the occurrence of the clunk but is still there approximately 35% of 2nd gear shifts. When I drained it, Fluid looked new so not too worried about wear but the experience isn't the greatest.

UOA: not available


Keen on some UOA of pentosin to see if there's a common trend on the potential shifter fork wear from excess aluminum seen and Amsoil synchromesh 5w30 experiences

[mav1178]

Amsoil Synthetic Manual Transmission Gear Lube 75W-90 virgin sample:


Amsoil 22k miles:

[Jesse36m3]

Originally Posted by mav1178

Amsoil Synthetic Manual Transmission Gear Lube 75W-90 virgin sample:


Amsoil 22k miles:

How did the amsoil feel for you after 20k?

[mav1178]

Originally Posted by Jesse36m3

How did the amsoil feel for you after 20k?

If you blindfolded me, I would've said it felt the same.

-alex

[venturaII]

I am currently using this fluid due to service work performed on my transmission at ~15,000 miles. OEM fill fluid was drained for the work, and after much argument and debate with the service tech and manager (who both wanted to use a Subaru GL5 fill), and finally with the help of the parts manager and their regional tech resource, Toyota LV 75W was determined to be the correct replacement fill.


Choice of fluid: Toyota-specified replacement fluid, LV 75W. (part number is in a different thread/post of mine elsewhere on this site...)
Miles on oil: ~7500
Climate: -10F - 90F
experience: Fluid very similar feeling to the OEM fill, but feels a little bit notchier...not quite as buttery-smooth as OEM fill. Second gear in cold weather will crunch a bit until fluid is circulating well. Warm weather produces very light shifts and lots of feedback from transmission. Slightly more gear noise noticed. Used a few times autocrossing without issue.
UOA: not available

[Vukodlac]

I'm currently experimenting with Amsoil 75/90w and with about 5000 miles, I still have cold start notchiness and down shifting resistance from 3rd to 2nd and so on. Once it warms up, shifts fine but takes a few shifts.

With factory fluid I never had this issue. I originally bought my car in Washington so its pretty cold 8 months out of the year. No shifting issues at any temperatures.

My conclusion; stick with you're OEM stuff unless your going to the track or something.

[Skegrider]

I am having a local Toyota dealer do a service on my 15' BRZ. They are telling me that Subaru and Toyota both recommend using a non-synthetic oil for the transmission. Is this correct?

[xxBrun0xx]

I waited until 26k miles to take out the factory stuff. I've got a TRD Quickshift kit and noticed that the gears were very crunchy when cold prior to the change. Went with Valvoline synthetic 75w90. Found a lot of metal shavings in both tranny and rear diff. A few miles after changing fluids, all crunch was gone and shifts were smoother than ever when cold.

When warmed up, factory fluid always felt fine. After switching out, felt about the same when warm.


Subaru has historically used their own "Extra S" transmission fluid in all of their vehicles. This fluid is non-Synthetic. Not sure if that's what our factory fill is, but it would explain the crunchy cold shifts.

EDIT: After about 5k miles on the Valvoline, 5th gear grinds at higher RPMs after transmission is warmed up. Going to swap out for something else, still not sure what. It's a shame because every other gear is butter, even when the car is cold.

[iarefluffy]

what is Extra S?

[venturaII]

Originally Posted by iarefluffy

what is Extra S?

It's GL5 rated and should not be used in our transmissions.

[football751]

Originally Posted by Vukodlac

I'm currently experimenting with Amsoil 75/90w and with about 5000 miles, I still have cold start notchiness and down shifting resistance from 3rd to 2nd and so on. Once it warms up, shifts fine but takes a few shifts.

With factory fluid I never had this issue. I originally bought my car in Washington so its pretty cold 8 months out of the year. No shifting issues at any temperatures.

My conclusion; stick with you're OEM stuff unless your going to the track or something.

Is that Amsoil Severe Gear 75W90 or their manual transmission fluid?

[JDKane527]

Is anyone running Pentosin 75W80 MTF2 GL-4 oil?

[mhughett]

Originally Posted by JDKane527

Is anyone running Pentosin 75W80 MTF2 GL-4 oil?

You're kidding, right? Try the search feature and you will find many threads of people using this product.

[JDKane527]

Originally Posted by mhughett

You're kidding, right? Try the search feature and you will find many threads of people using this product.

You must not have read the title of this thread.
I'm fully aware there are people out there running Pentosin. I pose my question to see if it is worthy of being in the contention for the "be all end all" fluids, as it has not been mentioned yet.