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I guess that depends on the definition of 'happy'. I mean, did they really have much choice in their spec? If for instance they felt it ideally ought to be on the mid to higher end of the 90w spec of the day, how could they have spec-ed that? I don't think there would have been a reasonable way to.
Perhaps Honda could confidently spec 90w, knowing that any choice, with any viscosity in the allowed 90w range, would not blow up any diffs (hence happy), even if the ideal fluid, that would have the least wear and least other negative effects, were at the higher end of the 90w spec.
That of course is pure speculation. I'm just pointing out that just because they spec-ed 90w, does not automatically mean anything that met 90w spec is automatically just as good for our diffs as anything else within that original 90w range.
I hope we're all on the same page that the discussion isn't if this fluid or that will blow up your diff (because hopefully everyone agrees that it won't), but rather what would the ideal fluid be, and why.
I know I'm learning a lot from this thread, and I want to thank everyone that is contributing to it!
Honda if they wished, could have got real specific about what exact viscosity and spec to use. But then the chances are you will end up with pretty much one oil from one manufacturer or if they really go for it an oil specifically made for the S2000 diff, sounds awesome but. Honda have to make a commercial decision, their product the S2000 has been sold all over the world and they have to look at what is available generically around the world to service their product. SAE90 is everywhere around the world SAE110 is not readily available everywhere, and if there was only one specific oil or a hand full of oils suitable for it would they be available globally? I doubt it so it makes servicing difficult in certain countries if Honda were to have taken that route. I suspect if Honda were to recommend an oil today as if the car was new, it would still be GL5 SAE90.
SpitfireS mentioned earlier in the thread that viscosity is tied in with the quality for protection in the diff and to a degree and he is correct. However for a given viscosity the quality is more important, as I mentioned earlier depending on the quality an SAE90 can out perform an SAE110 and visa versa. I have one customer who sprints and hill climbs his S2000 and with some experimenting we have him on 75w-80 in his diff for reduced drag, he is happy with the way it handles and no signs of excess wear. Swings and roundabouts.
When the manual was written the viscosity for an SAE90 ranged from 13.5 to 24.0 cst at 100c, so this by default means Honda were happy for an SAE90 anywhere in the viscosity bracket to be used, and most sat around the middle.
But they recommended a SAE90 including GL-5/6.
Including the GL-6 spec that was intended for high offset hypoid gears.
Would that not put it in the higher end of the range?
Having had a quick search of the net, it is not full of discussions about S2000 diff failures..
Well... that depends on what you categorize or recognize as a diff failure.
Example #1: A diff goes BOOM. Yeah, that's a failure.
Example #2: You find parts from the LSD on your drain plug. IMO that's a failure and it's not that uncommon (see the post I linked to) for Mobil1 SAE75W-90 users.
Example #3: You notice your car acting different and a diff oil change fixes it. IMO that's a failure. Sure, the sampe size is 1 here, me.
I would like to avoid all 3 and I think most would settle for #1 and #2.
So as far as I'm concerned I will stand by my personal recommendation of using at least a modern 75W-110 for the OEM S2000 diff.
And with this I rest my case
May I ask you this:
Have you driven an S2000, do you own one, do you daily drive one?
Have you experienced the chassis and how it 'talks' to you?
Have you seen the many posts here from people asking "Why does my car pull to the l/r a little?" and the standard answer is "Check tire pressure".
The tread starter usually answers "Ohh, but it can't be that because I checked them last month" and then they are persuaded to check again and then they usually post "You guys were right, one tire was off".
All this to show how good the chassis is and how little changes can be picked up by the driver.
So it comes down to you believing me about the LSD locking bias being noticed by me and that fresh oil fixed it.
There are no specs to be found about the Fuchs oil unfortunately.
there have been posts on here many years ago before comparing mobil1 75w90 to sae110 le1605 stating the diff actually runs cooler as their is less friction with the LE fluid, as for other fluids im not sure
But they recommended a SAE90 including GL-5/6.
Including the GL-6 spec that was intended for high offset hypoid gears.
Would that not put it in the higher end of the range?
Yes they recommended GL5 or GL6, but GL6 is not the requirement for this diff you must know this by now. It was just available and suitable. But as they are no longer available and nobody can even prove a GL6 performance any more, it is very much a moot point.
Originally Posted by SpitfireS
Well... that depends on what you categorize or recognize as a diff failure.
Example #1: A diff goes BOOM. Yeah, that's a failure.
Example #2: You find parts from the LSD on your drain plug. IMO that's a failure and it's not that uncommon (see the post I linked to) for Mobil1 SAE75W-90 users.
Example #3: You notice your car acting different and a diff oil change fixes it. IMO that's a failure. Sure, the sampe size is 1 here, me.
For the Mobil users who have found wear metal, is that down to viscosity or quality in your opinion? And what were the other factors such as type of use? How long had the oil been in the diff? Is there another issue with said diff or purely because of the oil?
Originally Posted by SpitfireS
So as far as I'm concerned I will stand by my personal recommendation of using at least a modern 75W-110 for the OEM S2000 diff.
And with this I rest my case
That is fine, but remember that is just your opinion. Not Hondas or they would have updated their recommendation for it. How all the other S2000's in the world have survived just fine with SAE90 is mystery
Originally Posted by SpitfireS
May I ask you this:
Have you driven an S2000, do you own one, do you daily drive one?
Have you experienced the chassis and how it 'talks' to you?
Have you seen the many posts here from people asking "Why does my car pull to the l/r a little?" and the standard answer is "Check tire pressure".
The tread starter usually answers "Ohh, but it can't be that because I checked them last month" and then they are persuaded to check again and then they usually post "You guys were right, one tire was off".
All this to show how good the chassis is and how little changes can be picked up by the driver.
So it comes down to you believing me about the LSD locking bias being noticed by me and that fresh oil fixed it.
I have driven one yes, but I do not own one. It did not push it too hard as it was not my car, but a lovely thing to drive it was. Not sure what tyres have to do with this thread but if it helps I run AD08's on my daily driver and love them
Originally Posted by SpitfireS
There are no specs to be found about the Fuchs oil unfortunately.
What specs are you after, I might be able to get them for you.
Out of curiosity: Is a xxW- 110 weight oil running hotter than a xxW-90 weight oil? If so, how much hotter?
In theory yes, thicker oils retain heat for longer. What the difference is though, only way to tell would be to test it. On the flip side to that, thicker diff oils can also take more heat.
Yes they recommended GL5 or GL6, but GL6 is not the requirement for this diff you must know this by now.
Well... GL-6 was intended for high offset hypoid final drives, and that's exactly what the S2000 has so I would say it IS still relevant.
The offset is the distance between ring center and pinion centerline.
I have no idea when a final drive is called 'high offset', the S2000 final drive set must qualify as high offset as Honda picked the GL-6 spec for it.
What is the GL-x spec anyway, what tests do gear oils have to pass? And what are the upper/lower limits?
Even if someone would spend the $/€40 and buy the spec from API, no test results are posted by oil manufacturers.
With viscosity one can see a number and 'read between the lines', but with API it's only pass or not, it's all a bit vague to me, to be honest.
Wouldn't it be nice if one can see oil A passed GL-5 test X with 52 out of 50-70 and oil B passed test X with 68?
For the Mobil users who have found wear metal, is that down to viscosity or quality in your opinion? And what were the other factors such as type of use? How long had the oil been in the diff? Is there another issue with said diff or purely because of the oil?
It wasn't wear metals in ppm, it was actual parts , fingernail size parts of solid metal, the 'ears' that broke off the side washers (see the posted drawings)
Something I would like to avoid and certainly not call 'normal' and/or acceptable.
The famous LE-607 was 20,9 cSt, btw, and would now be a SAE110.
It would not surprice me if other commonly available 1998 SAE 90 GL-5/6 oils were that viscosity too.
Those oils would be SAE 110 in 2018.
The main source of heat in a diff is friction.
Less friction = less heat.
Thicker oil = less friction.
Better oil = less friction.
Better additives = less friction.
It really is that simple.
I've seen posts of temperature tests with different gear oils, just as dedonderosa posted.
Here's one: http://www.fourwheeler.com/how-to/tr...d-towing-axle/
It's a 2006 test.
Scroll down to the end to see the list of temperatures.
Remember the LE-607 is a 2018 SAE 110.
I did a temperature test too once and posted it here, running LE607 IIRC but not before/after comparison.
Can't find it... could be it was in a xviper post.
As far as I know Honda didn't even remove the GL-5/6 spec in the later, past 2004, owner manuals. IOW: they didn't even look at it.
This is my 4.57 gear set.
Red is the ring center, green the pinion centerline.
The distance is the offset.
This is the (my own) OEM 4.10 gear mesh.
Imagine the pinion turning counter clockwise and how the pinion and ring teeth slide over eachother.
(Imagine a side washer 'ear' getting caught there!)
You're looking at the drive side of the pinion.
Hypoid gears create axial forces along the pressure angle on the pinion when it turns, so it's pushing against its conical bearings
That also means the pinion pushes the ring away, that's the load on the Torsen/ring bearing caps.
The higher the offset the more those forces are inline with the centerline (= good) but the more sliding between teeth (= hard on the gear oil: GL-6)
Last edited by SpitfireS; Oct 13, 2018 at 10:02 AM.
Reason: counter clockwise!
And no dedonderrosa, that was not the post I remember.
The oldest post of me on s2ki I can find via S2ki profile search is from 2013 and the temperature post was 2006/7 or so.
At the time I took temperature readings at the yellow dots with a Fluke and thermocouple.
I remember there was a little drop of oil on the drain or fill that acted like heat transfer oil and showed higher temps than just holding the sensor against the metal.
IIRC the temps were something like 60-70C or so after a spirited drive.
, fingernail size parts of solid metal, the 'ears' that broke off the side washers (see the posted drawings)
