s2kfoeva

So some people recommends amsoil 75w-110 but other people recommends mobile 1 75w-90.

Which one would be good for 2002 s2000 in Michigan? I am not sure how cooler weather (although it is hot in summer) in fall and spring affects the viscosity??

Not sure which one to get.

zeroptzero

Either viscosity will work well, I'd make sure to go with a full synthetic as it will flow better in cold temps, so either Amsoil or Mobil1 are good choices.

SpitfireS

It is not a belief, it is a fact backed-up by Torsen themselfs.
I'm sure others have noticed "strange behavior" but never linked it to the diff oil.
They probably spend $$$$ on suspension upgrades while all they needed was a $15,85 diff oil change.
Or they just drive the car hard on the internet or just in a straight line

Going around corners and accelerating out of them I find it hard to believe a competent driver doesn't notice the front being pushed out.
The next step is to link it to the Torsen.
That said: if you've never driven your car with the right oil you may not know any better.
Also, its not that there is a lot of price difference between the oils.
I would not hesitate to try it for $5 difference, would you?

Oh well....

zeroptzero

On long sweeping curves I definitely notice the car changing from neutral and oversteer to understeer under acceleration. The LSD lockup feels different with 75w90, 75w110, and 75w140 fluids I've used.

If I can get my hands on some LE1605 from Indymac that will be my next differential fill. It is a straight SAE 110 viscosity, which matches up well to the old SAE 90 spec. Looking forward to running it.

S2oooNvegas

All i will put in my clients cars is LE607/1605. Seen far too many failures with the mobil 1 junk as i call it.
The amsoil severe gear seems pretty good though i have no reason to recommend it. I have zero failures with the LE 607. So why go away from that record.
I ran it for 50k miles in my own s2k and i drag raced it every time i drove it.
I literally had over 10000 clutch dumps when i drained the fluid and it still looked like new.

sillyboybmxer

used LE since i got the car. 60k miles and 4.5 years

slipstream444

I have never been impressed with any of the LE iterations to date. I gave 607 a shot because of all the hype that circulated after it was introduced to this forum. I went from Amsoil Series 2000 75W90 (the predecessor to the Severe Gear line) with about 12,000 miles on the fill (it drained clean and as blue as it went in - the only recent color coded fluid by Amsoil that I can remember). I ran the LE for less than 10,000 miles and changed it out due to increasing noise in my diff - it came out filthy - the first dirty change since that diff was broken in. I will never use their product again. I went back to Amsoil and all gear oil changes thereafter were clean.

As for Mobil 1 75W90 - I think it is one of the best 75W90s available - even though it is on the thin side in comparison to a true 90 weight. I used it in no less than three of my previous cars (until I found Amsoil) - and would use it if I couldn't get Amsoil SG. My gear oil changes were very clean in my former Swift GTi, RX-7 and RX-7 turbo. All the supposed diff failures you have claimed are not due to Mobil 1 75W90 - that I can pretty much assure you. The only way you can make that claim and back it up is to show the oil and metal failure analysis of those supposedly failed diffs. If that analysis can show an oil related failure... Mobil 1 would have covered the damage. This is also true of Amsoil and Redline - they will cover any damage proven to be from an oil related failure. This is NOT true of Royal Purple - which I learned from personal experience - '99 Jeep GC (the link at the bottom spells this one out quite well).
Just so there's no confusion - there is NO gear oil that can protect a diff from abuse or stupidity... which are the two most common causes of failure.

As for Amsoil SG 75W90 and 75W110 - they are currently the best gear oils available and what I use in my S2000. Every fluid change in my diffs have been clean. That includes the OEM gearsets, Richmond 4.57 (that were not set up correctly), and the current Mazdaspeed 4.44 gearset in my car (Awesome! Thanks PuddyDad). Amsoil is also the fluid Puddymod Racing installs and recommends for every diff he builds.

At the bottom of this post is a link to a study from 2007 that was Commissioned by Amsoil to demonstrate how well its 75W90 compared to many of the popular fluids on the market. Most of the major tests were completed and published by an independent lab - a lab that services the entire industry. You might ask how this brings validity to the testing process? No certified lab will risk their certification and reputation for one company. Lab certification process is both complicated and expensive. Validity also comes from the fact that none of the companies whose gear oils were tested against Amsoil's have ever contested or rebutted the results. This test is widely circulated on the web and is available from several industry trade sites. One thing I really appreciate about Amsoil is they are a company that has been willing to spend the money and expend the resources to openly demonstrate their product is the best available in the retail market (putting your money where your mouth is) - and as they say (cue another over-used metaphor) - the proof is in the pudding...

One of the things you'll notice is Amsoil does not come out as the best performing gear oil in every individual test. However, in tests where it is not the top performer - it is one of the top four and its performance in any one category never detracted from good performance in another (making a one-dimensional oil... extremely good in one measure, but horrible in several equally important measures). More important than the individual tests is how a fluid performs overall - the sum of the parts - and Amsoil is decidedly the top performer when all performance measures are tallied. One of the best quotes in the overall analysis is: "A gear lube is only as good as its weakest link"* - and Amsoil didn't show a weak link. *Conclusion, Page 20.

Consistent to Billman's and my past experience - Mobil 1 75W90 comes in second - however it does fail one of the industry tests in that it sheared out of viscosity on the KRL test. The issue was Mobil 1 gear oil started out a little low in the viscosity range to begin with and didn't have to go far to shear below a 90 weight. The upside is Mobil 1 had one of the lowest shear reduction percentages - which means it doesn't actually shear much at all. I would like to see if Mobil 1 made an adjustment to the viscosity. Once again - Mobil 1 was very balanced overall, performing very well in every test other than the above mentioned. While on the thin side, it still provides all the protection the S2000 diff requires.

However, when it comes down to it - why use the number 2 gear oil when the number 1 oil is readily available? Amsoil Severe Gear.

Here's a link to the White Paper:
https://docs.google.com/viewer?a=v&p...wYzhl&hl=en_US

Make your own decision.

S2oooNvegas

Well slip, i dont live on these forums like i used to but in my world you are the first guy ive heard of with any issue from the LE product.
I run it in every s2k i build. I prob have it in 100 different client cars out there now. Not one failure in 6 years.
My buddies run it in their rock crawler diffs also.
Nothing else even comes close when it comes to coverage.
The torsen unit likes very thick fluid with the proper additives.
Water thin stuff or stuff that cant withstand what a torsen does to the fluid... causes it to wear out quicker and fail.

This is all ancient news... as in .... a decade old.
stock s2k comes with 90 EP rated gear oil. Diffs are fine, car is taken to dealer and..... 75/90 is pumped in.... diff goes BOOM soon after.
This has happened so many times its unreal and the info passed around early on.
To the point that i cant believe its being discussed now as though its new news.

run 90 Extreme Pressure rated fluid and your safe.
Run multi viscosity fluids that arent rated for this diff and risk your cash, its up to you.

INDYMAC

I'd have to agree with this. Right now I think there is no better gear oil for any rear diff than LE 1605, if your climate will allow for its use. Nothing protects better (based on specs, UOA's, no reported failures, and visual inspection of drain plugs). It runs clean too, unlike some of the others mentioned that I've seen pictures of here on s2ki.com.

The Amsoil severe gear series looks great on paper, as does Redline. But the UOA's for both are unacceptable IMO. And many complain of sludging and fine metal buildup on drain plugs. None of them come close to the LE 1605 specs either.

M1 75W-90 is probably the most popular gear oil in the S2000. And I have seen a UOA by xvipor that shows good wear protection. It seems to run clean too, but I have no personal experience with it. I would probably opt for the 140 grade instead though, since the 90 shears considerably.

zeroptzero

Many of the dealer fluid issues related to the use of their dual pump fluid improperly being used from the CRV. I'm not sure a really thick fluid like 140 is the answer as the diff may be affected by some splash lubrication, I think there is a happy medium around 110 where you get the thicker fluid protection along with sufficient splash lubrication. There isn't much wrong with a multi-viscosity fluid since the fluids are much thicker at cold temps then at operating temp so the 75 rating doesn't do any harm, as long at you get the proper hot temp viscosity protection. Just a theory though, I might have some better data at the end of my next run.