Absolutely serious.

When I clean the drain plug I only get a very small amount of what looks like graphite - as in barely anything at all on the plug. That's why I've stayed with it.

I've seen Redline come out of a S2000 diff after 10,000 miles and it looked like mud. I've also seen Mobil 1 75W90 come out of a S2000 after around 8,000 miles and it was relatively clean.
I really found the Amsoil Series 2000 75W90 to be a superb gear oil, but the Severe Gear line seems to be just as good. The 75W100 works outstanding with my Richmond gear set.

If you decide to try the Amsoil, go around 5,000-7,500 miles on the first fill and then change it again. The first fill will clean out any residual crap. You can pretty much go as long as you want on the second fill, but you should notice a reduction in fuzz on the mag plug after the first fill.

I tried one fill with LE and ran it for around 5,000 miles. When I drained it out the mag plug was covered with crap and the fluid was extremely dark.
I drained it because my mileage had gone down noticeably after the LE fill (2-3 mpg compared to Amsoil Series 2000). The previous 2 fills had been Amsoil Series 2000 75W90 (after breaking in the 4.57 gears). That fluid came out clean with nothing more than a graphite like smudge from the mag plug.

I use the Amsoil SG 75W100 because of the Richmond gears. You can run it with OEM gears as well, or use the 75W90. Either gear oil is outstanding.
I think the LE product is better suited for track use where the temps are always high. The Amsoil works better for everyday (hard) driving and covers a much wider range of temperatures. I would use Amsoil on the track as well.

 

can you address the sae rating change?

the le 1605 is a 110w, which should be the equivalent of a 90w prior to the change in rating guidelines.

doesn't that mean we should be using amsoil 110w as well, or is LE the only company to utilize the new sae guidelines?

 

I think Slipstream is referring to AMSOIL SVT 75W-110 as the new gear oil he uses. Although I haven't seen a UOA from an S2000 on this gear oil, everything I've read about it would lead me to believe it is an excellent choice. M1 75W90 has been a proven performer in the S2000 also. I'll be trying LE 1605 in my S2000 as a replacement for LE 607 soon. It is hot here in Texas and I'm starting to hear a little more gear whine as the OAT's rise. I'm not interested in MPG's as much as protection, since my car is not a daily driver. LE 1605 is semi-synthetic now, so we'll see if it runs cleaner than 607. That's what LE said when I discussed the new product with them. Sludging is not a good thing IMO.

 

Correct - 75W110 is what I meant (I should read my posts more carefully).

Gear oil specifications changed in the past 2 years to be more specific. 90 weight covered a broad viscocity range, to include what's now the 110 weight range. In fact, LE607 was closer to a straight 110 than a straight 90 weight.

 

I personally believe daily driving will not cause diff temps to get hot enough to see any benefit from the LE - even in Texas (I was stationed in OKC when I ran LE607 - and the summers were pretty hot) - and even with the hardest of street driving.

LE is just too thick IMHO for daily use, which leads to increased wear until the diff gets to operating temperature. That can be as much as 15 minutes in the summer time, and may not happen in the winter.
If you track your S2000, I believe diff temps get hot enough that LE may provide slightly better protection at peak temps.

Please post a UOA for the 607 when you change it out.
I plan on posting analysis numbers for SG 75W110 in the next few months when I change it out.

 

^
that'll be cool

 

I won't be doing anymore UOA's on 607. I don't see any point in it now. But here's a couple of UOA's that I've done in the past:

http://www.bobistheoilguy.com/forums/ubbth...true#Post706815

You'll notice that the SUS viscosity #'s indicate that LE did infact comply with J306. The original 607 formula had a SUS@210F of 104.7 I believe. My first sample probably had some residual gear oil (Pennzoil 80W-90 GL5) affecting the SUS, so the second sample was probably more accurate.

Here's another post where I compared some other gear oils to 607 in the S2000:

http://www.bobistheoilguy.com/forums/ubbth...true#Post801388

Hopefully, you'll remember to do a UOA of SVT 75W-110. I've never seen a UOA of any AMSOIL gear oil. Thanks.

 

wrong fluid. Must be GL5 or better. I dont think that GL4 is a hypoid lube. I wouldn't put that in your diff.

 

The MTG is for some manual transmissions (not recommended for the S2000's). You should have no problem returning it if it's unopened. That's why I buy directly from Amsoil.

If you bought it from an independent dealer (not Amsoil directly) and they give you a bad time - call Amsoil customer service. If they try to tell you the MTG is the right fluid - refer to these posts.

You want either Severe Gear 75W90 or 75W110. The SG 75W90 should be fine for just about any driving with stock gears. 75W110 for 4.57/4.56 Richmond gears, if your car sees moderate track time, or a lot of high temp use.