The additives in synchromesh could cause the LSD clutch plates to slip excessively and make the diff act more like an open diff.
Well I'd better check into this. Good catch. I've had it in the trans. a couple years with no issues. I change the trans oil every 2 years anyway so nows a good time to see. Thanks for posting this.
The additives in synchromesh could cause the LSD clutch plates to slip excessively and make the diff act more like an open diff.
Friction modifiers reduce friction for clutch type differentials that are aggressive and need to slip more. It will make the problem worse.Could I add friction additive. We have small bottles of this for the GM and Ford limited slip diff's.
Good info!
Is the Honda MTF silver bottle with white cap part number 08798-9031 and how many bottles go in to the gear box?
Thanks,
I've heard good things about the Amsoil MTF, but has anyone tried the Torco MTF?
Friction modifiers reduce friction for clutch type differentials that are aggressive and need to slip more. It will make the problem worse.
Great post Honcho and thank you for the elightenment. Guess I'll swing by Honda tomorrow morn. If someone will refresh my memory, 2 qts? FWIW, I did remove the small filter to clean 2 years back and she was clean as could be.:wink:
They do. It is a wet clutch type. 95+ use a helical type. NSX-R uses a wet clutch type with increased preload.
The additives in synchromesh could cause the LSD clutch plates to slip excessively and make the diff act more like an open diff.
I've heard good things about the Amsoil MTF, but has anyone tried the Torco MTF?
so some questions I am hoping someone can chime in on to clarify for me:
1) The GM cocktail is widely agreed it makes things smoother and less notchy, but with the possiblity of adverse long term wear effects on tranny...correct?
Correct. The friction modifiers in the GM fluid improve the engagement of the shift arms/selectors and synchros on your mainshaft and countershaft. But, they may cause adverse effects on your differential, which also uses friction between clutch discs to engage the locking function.
2) Is the GM cocktail synthetic? Is the Acura White cap synthetic?
Unknown. Anecdotally, I have heard the White Cap is a synth blend.
3) the knock on the GM cocktail is that it is too thin, so could a person develop a new "cocktail" that has maybe one part GM FM, 1 part GM Synchro, and 1 part Acura white cap? or is this essentially defeating the purpose of the FM?
You could, but it would be trial and error testing on a very expensive transmission.
4) Do we have wet clutch applications in our cars? (I am all OEM, don't track....occasional use, the occasional longer freeway ride , driven only in spring/summer months)
The reason I ask is that on the Amsoil site, it says not for use in engines, or wet clutch applications....yet it says it is recommended by many manufacturers, including Honda. Seems kind of
contradictory if we have wet clutch applications in the NSX? Note that it says it is a direct product replacement for the GM MTF fluids?
1991-1994 NSX 5-speed manual cars have a wet clutch type differential. 1995-2005 NSX 5 and 6-speed cars have a helical or "torsen" type differential. The 1991-1994 NSX differential is different than most other Honda MT cars, so I suspect the "Honda recommends" probably applies to the Civic/Accord/Integra product line instead, which is what 99.9% of potential customers are probably shopping. Because you do not track your car, the GM stuff probably is fine since you do not really need limited slip functionality. Moreover, it likely would take tens of thousands of miles for any premature wear to show up in the differential clutch pack. So, even though you may damage your differential, your practical application means it doesn't matter. The car will still work, but your rear wheels will not lock on acceleration anymore or as much. You probably won't notice it.
5) I am actually leaning mostly to an all Amsoil application of their 5W -30 MTF....however, I see they also offer another "heavy duty" type of MTF, for higher horsepower engines, however, I will assume that it is not going to work for us....it was SAE 75-90 or something?
Honda originally specified 5W-30 motor oil for the trans in 1991. The MTF is a much improved formula designed for the wet clutch diff, but it is still based on that weight oil. If you do go Amsoil, I would stick with the 5 weight stuff.
6) if we are "mixing cocktails" anyway, why not develop the best of all worlds....ie: 1 part GM FM, 1 part Honda white Cap, 1 part Amsoil? (shaken or stirred...just kidding) but would this be horribly bad to mix brands? I guess that is why I am wondering which is synthetic and which is not....I can see mixing all synthetics, but not organic and synthetic.
See # 3 above.
I guess my wish list is to keep the same buttery smooth shifting and almost no notchiness I have now, but not endanger the future reliability of my tranny...I plan to keep this car a long time...or at least until I can afford a second gen NSX....(which may be a VERY long time)
I have read over so many posts and different threads on this tranny fluid issue...and its almost like there is a FORD vs GM, or Coke vs Pepsi dialogue...so is it really just personal opinion, or is there any actual fact or technical logic to support using (or not using) a given brand....
Bottom line is this: your transmission is lubricated and cooled using a pressurized and filtered oil system that also lubricates the differential clutch pack. This is different than most passenger cars. Honda designed the system and tested it over many cycles using many different oils. To date, they have concluded two oils are safe to use in the NSX transmission: 5W30 motor oil and Honda MTF. They did not test any other oil. The issue in all these threads is not that aftermarket oils will damage your transmission (except for the Amsoil, which specifically says NOT to use in our type of trans), but that we simply don't know what the effect will be because Honda never tested it. Running it for 50,000 miles and saying my trans shifts great is not testing. That differential clutch pack may be completely shot for all they know. The only way to test for sure is to open up and inspect the trans pre-oil. Then run it for a long time. Then, open the trans again and check for wear/damage. I guarantee you none of the aftermarket companies have done this with a 1991-1994 NSX trans. The only company who did is Honda. Dozens of times.
Accordingly, all this is is a risk proposition. If you put anything else but the two oils above in your NSX, you don't know what it will do to your trans. Maybe it will be ok. Maybe it won't. If the nice shifting action of the Synchromesh is valuable to you, then perhaps it is worth taking the risk. For me it isn't. I track my car and have seen my trans opened up. My NSX has had nothing but the Honda MTF and the internals showed no signs of wear over 80,000+ miles. That's good enough for me, even if I have to wait a few minutes for the trans to warm up before I get the "butter" shifts. YMMV.
Hope this helps clear it up.
When you guys say "New Honda MTF Whitecap", is that referring to this? Genuine Honda Fluid 08798-9031 Manual Transmission Fluid
Accordingly, all this is is a risk proposition. If you put anything else but the two oils above in your NSX, you don't know what it will do to your trans. Maybe it will be ok. Maybe it won't. If the nice shifting action of the Synchromesh is valuable to you, then perhaps it is worth taking the risk. For me it isn't. I track my car and have seen my trans opened up. My NSX has had nothing but the Honda MTF and the internals showed no signs of wear over 80,000+ miles. That's good enough for me, even if I have to wait a few minutes for the trans to warm up before I get the "butter" shifts. YMMV.
Hope this helps clear it up.
.......My NSX has had nothing but the Honda MTF and the internals showed no signs of wear over 80,000+ miles. That's good enough for me, even if I have to wait a few minutes for the trans to warm up before I get the "butter" shifts....
...... Then I switched over to the Amsoil MTF after three years on the GM blend (even though Amsoil said it wasn't recommended). Ran that for about 3.5 years and noticed that the LSD felt slightly more aggressive (which I liked). Fast forward to now, and my car has been in a rebuild state for the past 1.5 years all apart. The transmission was opened up, and all synchros looked new. Clutch pack discs were measured and were within spec. It was reassembled according to Type R specs. So, after seven years and 70k miles with GM FM blend and Amsoil MTF, the transmission was in perfect shape.
Honda does not know all and they are slow to react to market and new product offerings. This is for good reason - to cover themselves. Bottom line is do your own research and be prepared for the consequences.
When I eventually put my engine and transmission back in, I've already purchased the new Honda MTF white cap stuff to try in it. Why not?
Good luck.
Dave
First of all very nice post by Honcho,To date, they have concluded two oils are safe to use in the NSX transmission: 5W30 motor oil and Honda MTF. They did not test any other oil. The issue in all these threads is not that aftermarket oils will damage your transmission
....I totally get how this becomes a bit of a risk proposition, but if the "risk" of a premature worn out tranny after say 200,00 miles is the effect of having a smoother shifting and more pleasurable driving experience, I think I would be willing to take it, because at my 3000 miles a year (maybe) thats a long time away....
Friction modifiers reduce friction for clutch type differentials that are aggressive and need to slip more. It will make the problem worse.