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Trans oil: Redline MT-LV or MT-90? | Diff oil: Redline 75W85 or 75W90

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18K views 70 replies 24 participants last post by  mazzjpc21  
#1 ·
Trans oil:
Both are GL-4. MT-LV 70W/75W matches the OEM viscosity. Some have said that the OEM viscosity is so thin for fuel economy etc. at the expense of better feel. My question is, has anyone used the thicker MT-90 75W90 after break in and had good experiences with it? I'm sure it takes longer to warm up, but does it improve feel after warm up? I live in a SoCal. Thanks.

Same question for the Diff:
75W85 GL-5 gear oil would be the Redline recommended diff oil
but would a better choice be for better protection and less wear be the thicker: 75W90 GL-5 gear oil?
 
#2 ·
I have been running Redline MT90 in my gearbox for over a year. Definitely feels a bit notchier on cold days before it warms up but if you are in SoCal you shouldn't have any issues. The shift feel is a bit smoother and I hope that it will give a bit of extra protection for my gearbox over time. The stock fluid is REALLY thin. No experience on running 75w90 on the diff, I am using Redline 75w85.
 
#9 ·
MT-LV and MT90 are polar opposite sides of the spectrum. If you track the car you may need something thicker. If not even the MT-LV is slightly thicker than OEM fluid. If it really makes you feel better you can step up to MTL, which is what I have been using without complaints for about 7k miles now.
 
#11 ·
I changed the factory MT & Diff fluids @6000km.

I used Redline 75w85 GL5 for the Diff and MT-90 GL4 for the MT.

With the MT-90 the shifts where notchier, especially when cold.
I struggled to go from 1st to 2nd many times.
When warmed up it was ok.

So I changed to MT-LV GL4 and the "problem" went away, I very happy with the shift feel.

I do not track this car very often, if I was on the track every other weekend I would have kept the MT-90 for better protection under track conditions.
 
#15 · (Edited)
Interesting reading:
Walter Motorsport is a company specializing in gearboxes.

On my ex mx5 ND2 I tried the Redline MT90, when starting it was really painful to shift into 1st and reverse, I don't know if it's due to the additive which is supposed to improve synchro locking (and I don't know what to think of this kind of additive on global lubrication either...).
When hot, the Redline was good, good feeling, smoother, easy gear changes even if the 1st and reverse were still a little recalcitrant.
I won't do it again.

Then I put the Ford Motorcraft, I preferred it, it's even more pleasant, a little less bad when cold.

I have just put the Ford Motorcraft also in my GR86 (3000kms), it's smoother and more pleasant than the oem oil.
When cold the 2nd is a little hard to get in but it heats up quickly and it works very well afterwards.

Redline 75w80 in my diff, little point I think for thicker oil, and our engine is not overpowering so it might make the work easier lol.

I put the Motul Gear300 75w90 in my previous car before my mx5 (edit, I mixed up my memories), it's a sure value too.
 
#20 ·
Looking at my trans UOA vs latapx’s with MT-LV in my trans and MT-90 in his, wear metals per mile look very similar other than aluminum, which is higher for him. That said, he tracks his car much more than I do, and he's a much faster driver than I am, so he may very well be stressing his transmission much more than I am mine and similar wear metals/mile may actually indicate superior protection. It's hard to draw a conclusion from just two data points, but to my eye I'm not seeing any red flags for either oil in the UOA.
 
#21 ·
UOA analyzes are something precise, in any case which needs to be precise to mean a semblance of something,
What is the procedure for collecting a sample to make a UOA ?
When we see how quickly the particles are deposited at the bottom of the containers by gravity, imagining that it must be the same in the crankcases of the car.
I find it hard to believe that this does not distort the results, not to mention the presence of the oil filter for the engine oil and the magnetic plugs for the diff and sometimes the gearbox.
 
#30 ·
Trans oil:
Both are GL-4. MT-LV 70W/75W matches the OEM viscosity. Some have said that the OEM viscosity is so thin for fuel economy etc. at the expense of better feel. My question is, has anyone used the thicker MT-90 75W90 after break in and had good experiences with it? I'm sure it takes longer to warm up, but does it improve feel after warm up? I live in a SoCal. Thanks.

Same question for the Diff:
75W85 GL-5 gear oil would be the Redline recommended diff oil
but would a better choice be for better protection and less wear be the thicker: 75W90 GL-5 gear oil?
I swapped the OEM trans oil to Redline MT-90. I was shocked at how watery the OEM oil was. However, the MT-90 makes the 1-2 shift tricky until it gets warmed up, so I am thinking MT-90 is a bit too thick. My next trans oil change will be to MTL75w-80, which I think will be ideal. In the diff, I use Valvoline 75w-90 and noticed no difference from the OEM oil.
 
#32 ·
Interesting, That table appears to be sorted by 100°C kinematic. The Pennzoil Platinum 75W-90 has higher 40°C than all others, but near the middle @ 100°C. It must be super thick when cold. More often the 40C and 100c follow one another more closely, except in diluted samples.
Chart of Viscosities from table: (resolution isn't great because of difference of scale.)
Image
 
#34 ·
Interesting, That table appears to be sorted by 100°C kinematic. The Pennzoil Platinum 75W-90 has higher 40°C than all others, but near the middle @ 100°C. It must be super thick when cold. More often the 40C and 100c follow one another more closely, except in diluted samples.
Chart of Viscosities from table: (resolution isn't great because of difference of scale.)
View attachment 48584
Thank you for making this, I had a rough picture in my mind but this is much better. No wonder ford motorcraft is smoothest at low temperatures among 75w90 fluids.

Yes, it is sorted by 100°C kinematic.

Thanks for posting that chart! If you want to add another option, Ravenol MTF-2 75w80 is 35.1 cst at 40 C and 7.4 cst at 100 C.
Thanks, will add it.

Vis@40°CVis@100°C
Toyota LV 75W MT305.7
MOTUL GEAR POWER FE 75W30.75.8
Redline MT-LV 70W/75W29.86.5
MOTUL MULTI DCTF34.77.1
Ravenol MTF-235.17.4
Royal purple SYNCHROMAX397.5
Pentosin MTF2 75w8038.37.7
AMSOIL Synchromesh 5W-3049.410.1
Redline MTL 75W8050.810.4
MOTUL GEAR POWER 75W-8069.410.5
Redline MT-85 75W856212
AMSOIL Manual Transmission Gear Lube 75W-9080.314
MOTUL GEAR 300 75W-9086.214.2
LIQUI MOLY High Performance Gear Oil GL4+ 75W-9081.514.3
PENNZOIL PLATINUM GEAR 75W-9010815.3
Ford Motorcraft XT-M5-QS 75W-907615.4
Redline MT-90 75W908215.5
Penrite PRO GEAR GL-4 75W-9010517.4
 
#35 ·
This list makes me wonder the naming conventions of these oils. AMSOIL Synchromesh 5W-30 in the middle of the viscosity values of 75W(75-90) oils? SAE xW20-40 engine oils have similar kinematic values as these, again 75W(75-90) oils, explanation????? 5w30 range is 9.1-11.3, 0w20 is 6-9.7 (100°C cSt.) Are gear oils evaluated and classified differently or to different standards than engine oils? And the Pennzoil I mentioned earlier looks like a straight SAE XX weight oil.... to me.
 
#40 ·
This thread has perfect timing; I was thinking about doing the manual trans and diff fluids over the summer @23k mi on my '22. Just for the sake of warranty purposes, I assume that all of the fluids discussed here so far meet the minimum requirements as far as Toyota is concerned? Part of me was a little paranoid and wanted to get the stuff from the Toyota/Subaru parts dept counters, but part of me realizes that's probably silly...
Not all of these match exact specs. If you want to follow specs in manual, you need GL4 75w fluid in transmission and GL5 75w85 or 75w90 fluid in diff.
 
#49 ·
#50 · (Edited)
#51 ·
I ordered both the Red Line my MT-LV for the manual, and the 75w85 for the diff, from the place I always used to trust for years when I had BMWs: FCPEuro. They are backordered on the MT-LV until mid-July like everywhere else is, but I don't really care, I just wanted to order from a place I was familiar with. I've gotten fluids from them multiple times with zero trouble.