brimstone

Alright,
I've read pretty much all I can handle in ~8 hours of reading, and finally I have some questions.

I've been giving it some thought, and I think it is also important that I outline my driving conditions because they differ so much from the average US driver:
I live in Istanbul, Turkey; my car is an EUDM '06 (8900rpm redline/2.0L, VSA but no cruise control) --has 4950kms (3040mi) on it. 80-120mph (sustained highway speeds (20-30 minutes per run, multiple runs per night) and bumper-to-bumper traffic (between 0.5-1.0 hours on average per day) is all in a single day's s2000 experience here. I get to frequently accelerate using VTEC in all gears.
For the record: I shift before redline, only hit the redline once since beginning of ownership, usually dont use all of 1st gear when accelerating, and I take my sweet time to let the engine heat up completely before I accelerate hard after a cold start.


a.) The differential fluid suggested by Road_Rage is LE607 90W. I found his reasoning to be sound, logical, and unbiased, so I've decided to go with it and have ordered 2qts from Rick's. Here's my question though -- my car is a '06 and has only 4950km (3040mi) on it--its only been 5 weeks since purchase. The manual suggests 40,000km (25,000mi) or 2 years before the first differential fluid change--even the "extreme condition maintainence schedule" suggests 24,000km/15,000mi or 1 year. I know that the differential is also subjected to a break-in period just like the rest of the car, and I was just wondering whether or not changing the differential fluid at ~5000km/(~3000mi)/5 weeks is dangerous/harmful to the break-in/longitivity/reliability of the differential.

b.) What would be the differental fluid change interval for someone who drives his S following normal US traffic laws (~65mph on highway) follow, and what would I follow compared to that interval? I'm basically asking what the general concensus is for changing diff fluid when using a non-synthetic oil like the LE607, and asking for any tips you can throw at me while you're at it.

c.) The discussions on "GM Synchromesh Friction Modified" were done mostly in 2004, and there was some discrepancy about whether or not it would be as effective in MY2004 and up transmissions with the carbon(-fiber? right?) synchros.

d.) I found a site that sells GM parts directly--but they don't ship internationally. Please PM me if you know of a site that sells GM Synchromesh FM and ships internationally because I've been getting the most ridiculous answers from dealers here. One tried to convince me that they used "ATF-3" in all their cars --I feel sorry for the manual transmission GM owners.

Edit:
Thread where Road Rage explains the truth behind 90w, the thread that convinces those who are yet unconverted: http://forums.s2ki.com/forums/index.php?showtopic=185775 (also can be found in the sticky "Oil, fluids..." under "The truth about 90w diff oil".

S2KenC

I personally 1st changed my differential fluid at ~12k miles. I replaced the fluid with Mobil 1 75w90. In retrospect, I would have changed out this fluid much sooner...probably around 6k miles or so. The fluid that came out was really dark. The magnetic drain plug did have very very fine shavings on it but nothing to be too alarmed about since this seems to be the norm.

I changed the diff fluid again at 23k miles. The fluid that came out again was really dark and again very very fine shavings on the drain plug. This time I changed the fluid to LE607 90w. I'll probably leave this fluid in for 10k miles before I change it again.

For the transmission, I've had good succes with Honda MTF. I haven't found a reason to change to anything other than this.

INDYMAC

If you've read the "oil journals", you're as educated as any of us are about tranny and diff lubes for the S2K.
Personally, I don't think it's too early to change your diff fluid with LE 607. Since it is still breaking in, I would change it again at 15K miles to get more of the metal wear particles out of there. Then change it every 15K after that.
If Honda MTF is working well for you, then stay with it. If the tranny becomes too notchy for your tastes, then try GMSMFM, Amsoil or RL MTL. They have all produced improved shifting (at least for awhile) by most that have tried them. There are some other lubes that Road Rage has recommended to try recently, but I don't remember the company that makes them (MTF-P?). I think I will try the new Acura Precision Crafted MTF next (currently using GMSMFM). They claim it is improved over Honda MTF, but we'll see...

xviper

Change it now. That first change may be the most crutial of them all. It contains the most in the way of break in shavings and debris. Even thought the magnet will hold most of the big particles, it's not a bad idea to get that out of there early. Then do it annually. Our rear diffs are pretty small for what the car asks it to do. A fluid change is cheap and is small insurance to keep it healthy.

You state the following:
But just before this, you posted:
I don't know about your European owner's manual, but mine would make this kind of driving a condition of the "extreme or severe" schedule. "Normal" no longer applies.

Although I'm in agreement that LE607 makes for a good diff fluid, I was not as moved as you were in that I don't believe it is the "end all, be all" of diff fluids for this car. There are many other very good rear diff fluids for this car and history has proven this.

Again, don't know about your manual, but mine states a fairly long change interval for the tranny fluid. Honda MTF has proven to work very well for long periods of time for many owners. Don't go putting something different in if your tranny performs well for you. Don't try to fix what isn't broken.

brimstone

Thanks guys. Your advice has been, as always, most helpful.

I'll change out the diff fluid as soon as I receive the LE from Rick's, and change it again at ~24,000km, and keep changing it at 24,000km intervals.

I have been noticing a more and more noiser 1st and 2nd gear experience lately, and thats what got me thinking about swapping the current with GMSMFM. I seem to be "feeling" more and more from the stick, and I've also lately been hearing some grinding putting into 1st gear at near-stop (1-2mph) speeds (the kind of grind that sounds like you haven't put the clutch all the way in--it isn't the full-blown so-embarrasing-you-should-move-to-another-country grind), but the car seems to be functioning just fine. I might just get the tranny checked instead, just not sure what exactly to do about the tranny yet.

If it means anything, when the transmission is fully heated up, everything feel much better and 1st/2nd are less noiser when engaging, there's also less resistance when putting it into gear, etc.

Road Rage

1) Diff gears are always hardened steel, often shotpeened - so metal shavings do little or no damage, but as there are other parts in the diff clutches, I agree with my Canadian friend Xviper that doing a change well before the manual "says to" is a good idea - 1000 miles or so is what I do.

2) I find it hard to understand how the gear oil can be causing notieceable stick buzzing and such after a few thousand miles - this is more likely wear-in effects, change of season, or hypersensiticity on the part of the owner. Doubt any fluid (although I still like GMSFM) is going to fix gross problems or perceived gross problems.

3) I also tried Specialty Formulations MTL-P and it is good - it shoild have long service life, which is the main thing since MTF shears down pretty fast. Shift quality in the S2000 box is I find more related to a proper warm-up. I double clutch the first few 1-2 shifts, then wait 20-30 minutes until the box oil is at SOT (std operating temp). Most racing boxes (and the S2000 box is as close to a racing box as most of you will ever come) are notiously "balky". I used to deliver Ferrarris, and they were horrid until they warmed up for 30 minjtes or so.

Hope this helps.

But no topic ever seems to end on this site - they just grow old.

P.S. I am getting a Nissan GT-R. Shame, shame, shame.

oakfloor

Well hello RR, I also run SF MTL-P, and it seems to work the same in cold or hot.
And I think does last longer than GMSFM. However its still a little more notchy than the GM lube. BTW is SF still around? I heard they were closed down.

INTJ

The torsen is notorious for wear. I've run them for years in audis and they have significant problems with accelarated wear when one wheel lifts. My interval for a track/ax car is 6k, no later than 10k. This is one of the reasons the pre-loaded R torsen came out. But it is hard to get around the tiny casing volume.

The LE is easily one of the best oils on the market, and otherwise I would only use straight wt redline.