2nd gear synchro FIX- MT owners read this thread

[roddy]

Originally Posted by gonzo

Check it again, it says the tran and diff gear oils can be 75w-85 and/or 75w-90

I'm looking at page RM-3.

Checked it again... Section 6-1, under specifications, page 348.

MANUAL TRANSMISSION

Gear oil capacity - 2.3 qt. (2.2L, 1.9 Imp qt.)

Gear oil type and viscosity - Use either of the following:
- "TOYOTA Genuine MG Gear Oil special II"
- Other gear oil that meets API GL-3 and 75W90 specifications.

No mention of 75W85 for the transmission...maybe the Canadian manual/spec is different .

[Esoteric]

To clarify in this thread, none of us who are advocating a thinner fluid are saying it is defined as the spec by Toyota / Subaru. That's clear in their documents. Ok

Thinner fluids are used by all manner of enthusiast and have been proven in many, many different types of transmissions and in everything from street use to full blow racing. We're talking HIGH loads. Ok, got that too

I wanted to hear it from the right person(s)...
Every year, I attend the PRI show. I made it a point and I spoke with several lubricant manufacturers (at least ten plus attend the Professional Racing Industry show every year). I wanted to know how they look at this situation and if this is something we should all be concerned with.
From what I gathered after speaking to a few respected people, the additive packs in the speciality oils we are discussing should be adequate in protecting the gears under most all conditions and that the gears themselves are not as dependent on viscosity as one might think. The additive packs also protect the synchronizers.
The take away was that thinner gear oil is not going to cause damage to the gearbox unless its providing far too little protection (overheated / depletion of additives).

Do you know what trend was extremely common amongst all the specialty racing oil manufactures i spoke with: Not only 75w85, 75w80... But 75w75 and 70w70 oils! This was new, even to me.
Modern additives have allowed for lower viscosity, even racing, while the gear boxes hold up and shifts are smoother.

Also...
The close cousin of our gearbox, the Aisin found in the S2k. Many, many people use Honda's MTF, rated in viscosity right around 75w80.


Take away: 75w80 as 75w85 GL-4 may not be what listed in the manual.
If your using a superior oil you should match the viscosity to the temperature range you expect to use and can even go with a thinner oil that allows for faster gear synchronization in your gearbox.

[gonzo]

Originally Posted by roddy

Checked it again... Section 6-1, under specifications, page 348.

MANUAL TRANSMISSION

Gear oil capacity - 2.3 qt. (2.2L, 1.9 Imp qt.)

Gear oil type and viscosity - Use either of the following:
- "TOYOTA Genuine MG Gear Oil special II"
- Other gear oil that meets API GL-3 and 75W90 specifications.

No mention of 75W85 for the transmission...maybe the Canadian manual/spec is different .

I'm going off of the manual that is posted on this forum, check that one out perhaps it's different from yours

[roddy]

Originally Posted by gonzo

I'm going off of the manual that is posted on this forum, check that one out perhaps it's different from yours

Ok, I see where you're coming from. It looks like a bit of a generalization, as it says transmission and differential. In my owner's manual it lists 75W90 for the trans, and 75W85 for the diff (with 75W90 acceptable as well). I'd be interested to see if your owners manual is any different than mine. Regardless, I chose to use Pentosin (75W80) on Gem's glowing recommendation, and it works great even at temps well below freezing.

Edit: yay...my 500th post!

[gonzo]

Originally Posted by roddy

Ok, I see where you're coming from. It looks like a bit of a generalization, as it says transmission and differential. In my owner's manual it lists 75W90 for the trans, and 75W85 for the diff (with 75W90 acceptable as well). I'd be interested to see if your owners manual is any different than mine. Regardless, I chose to use Pentosin (75W80) on Gem's glowing recommendation, and it works great even at temps well below freezing.

Edit: yay...my 500th post!

I will check my car manual to see what it says. I dont experience cold enough weather so i went with redline 85 and it def feels better

[roddy]

Originally Posted by gonzo

I will check my car manual to see what it says. I dont experience cold enough weather so i went with redline 85 and it def feels better

I'm sure the MT-85 will be fine. Others have tried it and reported good results. I used MT-90 for my first change, and it was a vast improvement over the OE fill. The only reason I drained it out was once the temps got below 40F, the shifting got pretty stiff. I skipped right over the MT-85 and tried a blend of MTL (70W80) and Honda MTF (75W80ish). I did this as an experiment to see if the transmission liked a thinner fluid and to use up some stuff I had laying around from other projects. This improved cold weather performance and effort substantially. I didn't want to spend $30 a quart on Pentosin until I was sure the trans would like a thinner fluid. If I had tried MT-85 for my first change, I may still have it in there.
Esoteric has some good points above ^.

[001BRZ]

Honda MTF 06 is working amazingly in my brz, I've started a thread on it in the Aussie section!

[gmookher]

Originally Posted by 001BRZ

Honda MTF 06 is working amazingly in my brz, I've started a thread on it in the Aussie section!

Honda's MTF uses some kind of sulphury-smelling compound that smells like gear oil.but, Its a GL4 just like Pentosin, unless your MTF-06 is different from our US MTF-2. The photo I found of the MTF 06 looks like nothing else I've seen.

Honduh MTF2 Virgin Oil Analysis on Bobistheoilguy.com shows a viscosity of 7.5cst at 100*C. most of people who are activley tracking their cars are using something that is designed to withstand more abuse than the OEM oil, in honda-land too.

There are lots of claims (and a VOA IIRC) that suggest Honda MTF is nothing but a 20(synth)/30(dino) weight oil mix with some EP additives thrown in for good measure.

As you are probably aware, Honda back in the day used to specify motor oil in their MT's until ZDDP started disappearing when the newer API specs came on the scene longside OBD2. I must be showing my age on this one. honda MTF "shears" down in weight overtime, as is common with fossil fuel oils.

I used Pentosin knowing its a full synth and that Honda is not. It will work great tho, as its very similar to Pentosin, which is a group IV/V oil mix. No dino in there like Honda, thats at best a III, as is the case in most semi synth formulations.

here is a basic breakdown, tho its fun to watch folks try stuff clearly not in the right range, just to try it..
Manual Transmission Oil Viscosities

ATF type MTFs: 6.0 – 7.5 typical
Honda semi synthMTF II 7.5
Royal Purple Synchromax 7.7
Pentosin MTF2 7.5

GM/Chrysler Synchromesh type: 8.5-10.0 typical
Torco MTF 8.35
Pennzoil Syncromesh: 9.08
Amsoil MTF (5W-30) 9.6
Red Line MTL 10.6
Honda MTF 1 10-11?

75-85 Gear Oils: 12.0-12.5 typical
Specialty Formulations MTL-P 12.0-12.5
Castrol Syntorq 75W-85 12.0???
Nissan 75W-85 12.0???
MT-85

90 weight Gear oils: 15-16.5 typical
Royal Purple Max Gear 14.5 (Published: 21)
Amsoil MTG 14.7
Pennzoil GL4 75W-90 15.3
Red Line MT-90 15.6

You choose, the Honda is a perfect oil, I would just change it out more frequently with track usage. Its the cheaper stuff to put into an aisin tranny compared to the german fluid.

[Dezoris]

After coming from 4 Hondas with 6 speeds including two S2000s I would never run Honda MTF again. Feels great for about 6k-10k miles but get a few track days in it and syncros get balky. It just does not hold up well. I am hoping the Pentosin does not have the same issues.

[gmookher]

this.

[getbent]

So is everying going to 75W80 simply to solve the performance in the cold? Nobody has any reservations that the operating temperature thickness of 75W80 (7.7 cSt) is significantly less than 75W90 (~15 cSt)?

[aced86]

Had the opportunity to drain and put the pentosin new fluid in today . Will report back over the next couple of days to see how it does. Also I stated I may be able to find a better price on this fluid through one of my wholesalers . Found out I get it for the same price as the website gmookher listed in his first post .

[001BRZ]

Interesting info guys on the honda oil, I think I'll try out some of the pentosin in the future!

[gmookher]

Originally Posted by 001BRZ

Interesting info guys on the honda oil, I think I'll try out some of the pentosin in the future!

seeing as you tried the honda stuff, I am VERY curious on your feedback on Pentosin, as a comparo