Gear box oil with OS Giken (gear friendly) ?

[asylum]

I had a OS Giken installed 2 years ago and made perhaps 1000 track miles since then. I used Castrol Syntrax Limited Slip 75W-140 because a thicker LSD oil is recommended with the Giken (Giken even recommends 80W-250). But now my 3rd gear synchro is going bad.

I am asking myself if the 75W-140 is a safe long term option for the gears ! Should I go back to a thinner oil ? But which one you recommend with the Giken LSD ? It seems that the Honda MTF is not recommended with the Giken...

 

[prym8]

Sorry to hear that about your tranny. Some of us with the OS diff have been posting in recent months about this -- check out RYU's thread and maybe do a search for the other posts that are scattered in other threads.

I think you could use MTF if you didn't care about low speed clunking noises when turning. Have you noticed those so far?

RYU uses the heavy OS fluid which seems to eliminate the noises. I started with 2qt+ MTF/ 1qt Motul 70w140and have worked my way to all 70w140, with less clunking but it's still a little obnoxious. I wanted to go to 90w140 but you are adding to my worries. I have a low miles 6sp I don't want to abuse.

Lastly there are WPC treatments you can read about in a MotoIq article online. This seems to help with noises so maybe a lighter oil could be used? With the cost of a teardown, this seems crazy to do unless everything is already taken apart.

 

[goldNSX]

I've wrote to asylum in another forum. Synchros are consumables on track cars.

 

[asylum]

With the Giken LSD and the gearbox synchros in the same oil, it seems that only a compromise is possible. Is it right if we summarize like this :

Gear box :
- GL-4 only (brass synchros friendly)
- thin like Honda MTF 75W80 (the synchros will slip more with thicker oil and not synchronize the shafts)
- no (or not to much) friction modifiers (the synchros will slip more and not synchronize the shafts)

OS Giken :
- very thick oil 80W250 or 75W140 recommended (otherwise it shudders or locks without slipping)
- no (or not to much) friction modifiers (otherwise it will slip to much, hence wear to much and not lock)

How to cope with that ? Using a GL-4 slightly thicker oil than Honda MTF ? Using Honda MTF and add a very little bit of friction modifier ?

- - - Updated - - -

Castrol is making a GL-4 75W90 "transaxle" that is made for vehicle having gear box and differential in the same housing. Maybe a good solution ?

 

[scammy]

I am using this one, Nick @applied built my gearbox and got the OSG WPC treated recommended it

 

[darock]

GL5 + bronce synchros is not good at all. I have seen GL5 corroding bronce gearbox parts in my Triumph. Sucks big time when you see your newly installed synchros all strangely worn with black dots and dimples all around after only 5000km. Bernhard

 

[asylum]

Have heard about that and that is why I would prefer to use GL-4. But I have also heard that the new GL-5 oils are less aggressive to brass than years ago.

 

[darock]

I think it was 2011 when I found the corroded synchros after two years of useage of the rebuilt tranny.

Also, GL5 stinks ... and all Honda Gearboxes only like oil that does not stink ...

Yea I know, its not that easy but anyhow a good rule of thumb.

In my NSX gearbox was some stinky oil when I bought the car. Shifting was hard, third gear synchro wasn't happy and the oem LSD was clicking while u-turning. Changed to MTF and the gearbox feels like new.

Bernhard

 

[asylum]

Talking with my mechanics, he said that when installing the Giken 2 years ago, he threw Honda MTF back in because shifts were totaly crap when he tried with the 75W-140. This oil is to thick for the synchros to bite. I did not know that and bleed with 75W-140 before this last trackday. So I think changing for Honda MTF will resolve the problem. We'll see.

 

[scammy]

I was told not to run the Honda MTF with my Giken

 

[prym8]

I've posted these before but anyway here are the noises when you run mostly MTF:

clip 1

clip 2

2 things.
-It is quieter now with heavier Motul 70w140
-the LSD is an awesome upgrade so I don't want to sound like a complainer. I wouldn't want to go back.

 

[RYU]

A few notes to share. As usual... Just my $0.02.

* I've broken-in the LSD with 2 track days and several hundred miles of Street driving. There is zero chattering noise now. Put it this way... I forgot they were suppose to make noise until I read OP's Facebook thread. I don't think about it. The OSG clutch still makes noise though

* I've gone thru 2 transmissions thus far. Synchros wear out quickly in the NSX regardless especially a track driven one.

* if you want to baby your trans, perhaps the answer is to sell the OSG LSD and put the stock one back in. It's a compromise and I have no long term experience yet to share. Will report back on my build thread if I notice abnormal synchro wear.

* I can say is the car has a tough time shifting into 1st gear at initial startup when ambient temps are below 60°F. Takes about 5 mins to warm up.

* I would keep my LSD even if it was noisy. It's awesome especially on a boosted car.

 

[austrian type-R]

Back in the days with my turbo ITR and the Cusco LSD I used the BMW rear transaxle (by Castrol) oil my engine-tuner recommended. It worked fine for many years. If I would have the Giken LSD in my NSX, I would run that Castrol transaxle oil again.

 

[asylum]

As said, I did not know that I was running the Honda MTF fro 2 years (the one for LSD you would put in a Intergra Type R for example). It worked great. No shudder of the LSD. Awesome traction on track. It is just since I put the 75W-140 that the synchros (especialy the 2nd to 3rd) seem not to bite.

 

[asylum]

No problem at the track today with the Honda MTF-3 :smile:

 

[BBVNSX]

You may want to have a look here:

http://www.nsxprime.com/forum/showt...-NSX/page49?p=1289465&viewfull=1#post1289465:

here:

http://www.nsxprime.com/forum/showthread.php/36427-Procar-Specials-NSX/page50?p=1312757&viewfull=1#post1312757

and here:

http://www.nsxprime.com/forum/showthread.php/36427-Procar-Specials-NSX/page50?p=1313011&viewfull=1#post1313011

good information from post 1210 to 1247

 

[speedracer77]

I'll throw in my 2 cents.

Note: OS-250R Not recommended for transaxle applications.

Talking directly with OS Giken they recommend a blend with 75w140 for transaxle applications. Their OS-250R you could use but only like 1/2 a quart (500 ml).

What we're using is a blend of Honda MTF + 1L/1quart Motul 75W140 and it seems ok for now - your mileage will vary as this is a race car.

 

[prym8]

Hey thanks for the real world feedback. The more info the better. [emoji3]

Please post up if you decide on changing your preferred gear oil, and if you see any premature wear in the synchros etc.

 

[RYU]

I received formal confirmation from OSG USA today supporting [MENTION=32598]speedracer77[/MENTION] findings. They no longer recommend the 80w250 oil for the NSX. A bit frustrating because just a few months back it was the best thing next to sliced bread. The stuff wasn't cheap either. Now I need to swap out the fluid to their recommendation - Motul Gear Competition FF 75w140

I posted the official dealer memo on my build thread.

- - - Updated - - -
[MENTION=24046]scammy[/MENTION] - I'm probably going to visit Nick this weekend. How are you doing with your 75w90? Are you experiencing any chatter, noise, or slippage?

 

[scammy]

[MENTION=20915]RYU[/MENTION] everything was working fine it was just the whine which Nick will tell you more about, the engine is out at present since its our winter here and should be back on the road for her 25th birthday in Oct

 

[M666 EDD]

Hi all. Does anyone have any updates on their oil choices?

I've been using Motul Gear 300 75w90 for the past 10 years, since I bought the car which already had the OS Giken diff. I don't have any diff problems but following the last removal of my drive shafts I did have a lbig eak from my intermediate shaft seal and I believe the remaining oil got very hot (had tough shifting at the time). Since getting the seal replaced the oil was just topped up, over 1L was missing from memory. The oil wasn't very old but does the oil degrade when it gets too hot? Perhaps I should have replaced all of it?

 

[Honcho]

Hi all. Does anyone have any updates on their oil choices?

I've been using Motul Gear 300 75w90 for the past 10 years, since I bought the car which already had the OS Giken diff. I don't have any diff problems but following the last removal of my drive shafts I did have a lbig eak from my intermediate shaft seal and I believe the remaining oil got very hot (had tough shifting at the time). Since getting the seal replaced the oil was just topped up, over 1L was missing from memory. The oil wasn't very old but does the oil degrade when it gets too hot? Perhaps I should have replaced all of it?

Might be worth trying this stuff:

https://www.rf-yamamoto.com/NSXmission/6.html

Yamamoto uses it with his OSG trans builds.