Kind of branching off from the 'broken diff' thread, where I mentioned that my S is now on it's third diff in 26000 miles. As three diffs in 26K has to be more than just coincidence, I started investigating diff lubricants. (Sorry if I'm going over old ground here.)

After interrogating my dealer today, it turns out that they put 'Dual Pump fluid', into my new diff, a Honda's own brand lubricant. They ensure me that this is the correct fluid.

However, thanks largely to the advice of the American guys on the Under the Hood forum, it seems that this Dual Pump fluid is completely inappropriate for the S2000, and is in fact meant for the CR-V. When I asked the dealer 'but isn't that what you use in the CR-V?' they said 'yes, we use it for all diffs.'

Now, this bit is a mixture of second and third hand information, so I hope I've got this straight, but I gather that this dual pump fluid, also known as VTM-4, is not GL-5 rated, meaning it's additives do not give it the performance needed under the high stresses it will encounter in the S2000's diff. A service bulletin issued by Honda USA, (and presumably by Honda UK although I can't locate a copy of it) states the recommended diff oil as SAE 80W90 GL-5 hypoid gear oil. Definitely not the same as this dual pump fluid stuff. All this has apparantly been backed up by the leader of the Honda USA technical division in California, who goes by the name of Woodwork on the US forum, and has said "do not put this stuff in your S2000's differential!"

And the result of using the wrong oil in the diff? Well, as stated, I'm on my third one, and the more I look into this, the more people I have found that have had diffs breaking, wearing abnormally, squealing, metal fragments contiminating the oil ......


The part that is perhaps the most worrying, is that my dealer says this CR-V fluid is the right stuff for the S2000 - and they are supposedly a highly reputable NSX appointed dealer. So the question is, what are other dealers in the UK putting into our diffs?

I will be speaking to Honda UK tomorrow to try and get an official line on the correct fluid - I'll be hoping for their cooperation, and I'll let you know what I find out.

 

I highly recommend Lubrication Engineers LE-607. Fabulous stuff. If it's not available in the UK, I may be able to send you some. PM me if you like.

 

My diff is running on Castrol Hypoid (I can't remember the rating - without checking the last service invoice - but I think it may be EP 75 - 80). Whatever, I checked the spec out and my diff is running on the right oil. It sounds like yours isn't.

The S2000 will use a different diff oil to front wheel drive cars, and to the rest of the Honda range. Although the NSX is rear engined I wouldn't mind betting the diff set-up is more similar to a front wheel drive car as the NSX engine is transverse.

The reason rear wheel drive diffs need a different oil is that they turn the drive through a right angle and to do this use "hypoid gears". The surfaces of these gears slide against each other when they contact and hence an extreme pressure oil (thus the "EP" part in the rating) is required. To achieve this quality the oil manufacturers use sulphur and hence the correct diff oil will smell heavily of this. If you check out a container of the oil your dealer has used and it doesn't smell of sulphur I would be 99% certain (I don't know if modern oils have found a substitute for sulphur yet but I doubt it and in any case I would tend to stick with something that has worked for many years) that you have the wrong oil!

If you have the wrong oil don't drive your car until it is changed (once the crown wheel and pinion start to mark, even if the diff doesn't fail ultimately, it will be noisy for ever)!!!!

 

Silkolene 90 in mine.

 

Well, I spoke to 'Georgina' at Honda UK this morning. She said she would ask her technical team for the official line and call me back. 6 hours late - no call back, offices closed for the day. Hmmm - it's an easy question, what's the proper oil rating for the s2K diff, and what have they put in my car. Either they're just extremely slow, or the question is giving them problems. So, I'll have to try again tomorrow - meanwhile, I'm having to put off driving the S for fear of doing harm.

 

The only official oil spec I've seen in the UK for the diff is 90W GL-5.

There aren't many pure 90W's around though - it's more common to find 75w90 or 80w90 multigrades. These are readily available in the right GL-5 spec. (If you're after a pure 90W GL-5 Miller's do one for example - but it's in their classic range. A pure 90w is unusual for a modern car...).

While the wrong diff oil isn't good, I doubt it's caused the kind of fragments in the oil failure you've had. I'm more inclined to think that the original diff went due to abuse. Then when it was repaired, the dealer didn't shim the gear pinion to ring clearance to spec, which would be far more likely to cause the diff gears to fail prematurely. Unless you have the remains analysed, you can't know though.

-Brian.

 

You could be right. I can't rule out abuse for both the previous diffs going, as I wasn't the owner for most of those miles. Nevertheless, I've read more than just a few comments now that the wrong oil can lead to diff failure, so I'm treating it as a serious concern. By the way, I'm interested to know whether these different diff fluids mentioned are ones put in by dealers, or by individuals. For warranty purposes, I'm happier to use what the dealer has put in, right stuff or wrong stuff, then on their head be it.

 

I had a problem with my diff outside warranty that arose after I asked the dealer to change the diff oil. According to the invoice they put the dual pump fluid in which is apparently a hypoid oil. I was told after checking this several times (and after it had been checked with Honda technical) this was what was put in all diffs EXCEPT FOR THE CRV.

Whatever, shortly after the oil change my diff started to make horrendous noises eventually leading to all sorts of examination, finding swarf in the oil etc. The bearing and crown wheel and pinion were knackered.

The dealer handed the repair to a local specialist (guy who used to be Senna's engine man!) and after stripping he was convinced the wrong lubricant had been used. After rebuilding with new parts (itself a fiasco as it took ages for them to turn up while my car sat stripped down on a ramp) they reinstalled and I've had no further problems (touch wood!). They used Castrol SAF diff oil, apparently a 'proper' oil used in v high performance cars (Lambos, Ferraris, etc). It's pretty expensive stuff (Pds14 per litre) but I wouldn't ake a chance on anything else from now on - the whole mess ended up costing me over a grand (it's a long story) even with some write offs from Honda and the dealer

 

Checked my service invoice last night and it is EP 80 - 90 oil that the dealer used for the diff.

 

[QUOTE=Mans Best,Aug 18 2004, 10:43 PM]
They used Castrol SAF diff oil, apparently a 'proper' oil used in v high performance cars (Lambos, Ferraris, etc).