[MGizzle]

Bruce, where do you get your Motul FF Comp from?? That stuff doesn't look cheap at all so I was wondering ifi you got a hook up spot??

I am a bit nervous going to synthetic though because I don't understand tranny fluids that much and have heard people say that it is not recommended for the STi 6MT. What difference can the synthetic oil have on the tranny?? Synchros??

[Neanderthal Racing]

Originally Posted by MGizzle

Bruce, where do you get your Motul FF Comp from?? That stuff doesn't look cheap at all so I was wondering ifi you got a hook up spot??

i get my motul fluids where a lot of people do: http://www.ltbmotorsport.com/motuloilfluid.html however, my sponsor http://www.rallysportdirect.com/shop/index.php carries motul brake fluid. where there is brake fluid you can usually find the rest. i'll be talking to nick as soon as i need another supply.

Originally Posted by MGizzle

I am a bit nervous going to synthetic though because I don't understand tranny fluids that much and have heard people say that it is not recommended for the STi 6MT. What difference can the synthetic oil have on the tranny?? Synchros??

i've only used motuls since the first change on everything. for every person who says synthetics are no good you'll see many more who swear by it.

better living through chemistry. live it.

[stretch]

Originally Posted by MGizzle

I heard that Synthetic oil for the STi sucks because our synchros use friction to work properly

...but isn't that what Redline MT-90 is for? This is manual transmission oil, not straight gear oil.

If people are running straight gear oil in the transmission, then the sloppy synchros would be expected.

Edit: MT-90 is GL4 when the STI calls for GL5. Redline's 75W90 NS is a GL5 oil and seems like the right stuff, but it (like Motul and many other synths discussed here) does not have any LSD additives. The tranny has two LSD's in it. Furthermore, many report the synchros not working well with this oil depsite the oil claiming "rapid synchronization", but again, this is probably because the oil was designed as straight gear oil (though Redline lists it as working for transmission, too).

I found this on the difference between GL4 and GL5 oil:

GL5 gear oil is a lubricant with very high extreme pressure performance needed for Hypoid gears where sliding and rolling contacts operate under very high loadings. This is achieved by incorporating high concentration of sulfurized additives. The downside to such high sulfur in oil is it tends to corrode yellow metals, so can ruin parts like brass synchronizers and some bushings. So any equipment needing GL5 performance is designed taking this limitation of the lubricant into account.

GL4 oils are much more friendly to yellow metals, and so are used in equipment where such high load sliding-rolling contacts aren't present. The designers of such equipment aren't as limited in the use of brass parts. So the bottom line is that if your equipment calls for GL4 it probably doesn't need GL5 performance, and you may be asking for trouble down the line if you use a lube it wasn't designed for.

[BM_STi]

Motul Gear 300 over here. Zero issues with the fluid and no grinds at all.

[IndySTi]

Originally Posted by BruceChapman

i get my motul fluids where a lot of people do: http://www.ltbmotorsport.com/motuloilfluid.html

Thanks for that, I didn't know about them.

Even better, they seem to have the best price for the Koni Sports that I have on my wish list!

[IndySTi]

Originally Posted by BM_STi

Motul Gear 300 over here. Zero issues with the fluid and no grinds at all.

Good for my DD in your opinion?

[Peleg]

07/13/2008 Update!

Did the major maintenance about 6 weeks ago. Went with the Valvoline 75W-90.....

4th to 5th grind and the trans is very very notchy.

Motul 300 Gear on the way. Hopefully this will make the gear box happier.

[PSTi]

Changed my fluid few weeks ago with Redline lightweight shockproof. Tranny shifts alot smoother and even on cold starts. With the Valvoline, it would stick in first gear when cold.

[Peleg]

The valvoline sucks ballz, 4th to 5th grinds, it sticks so bad on startup I have to shift from 1st to 3rd.............

[blindfold]

OEM Extra-S fluid, just split it with few local STi owners and it should be good to go

[lycan]

i know a lot of people have had trouble with amsoil but 3 years now and never a grind on any shift. even at the track.svg FTW!

[Peleg]

Originally Posted by blindfold

OEM Extra-S fluid, just split it with few local STi owners and it should be good to go

It's a shame the local dealers can't tell you EXACTLY what they put in the car and that you have to go through all this bs to find out, just a shame..........crappy dealer support and technicians I can't trust.

[rgarrett7]

I used Valvoline 75W-90 for a while. I am currently using Motul 300. I cannot really tell any difference between the two. My transmission is definitely a little hard to shift, especially when cold. 3 and 4th are always fine. 1st is always the worst, then 2nd. When it gets nice and warm, shifting is fine.

My '04 has 81,000 miles. No work on the tranny or clutch. I'm thinking about replacing the clutch fairly soon as preventive maintenance, though there are no symptoms.

[Peleg]

Originally Posted by stretch

...but isn't that what Redline MT-90 is for? This is manual transmission oil, not straight gear oil.

If people are running straight gear oil in the transmission, then the sloppy synchros would be expected.

Edit: MT-90 is GL4 when the STI calls for GL5. Redline's 75W90 NS is a GL5 oil and seems like the right stuff, but it (like Motul and many other synths discussed here) does not have any LSD additives. The tranny has two LSD's in it. Furthermore, many report the synchros not working well with this oil depsite the oil claiming "rapid synchronization", but again, this is probably because the oil was designed as straight gear oil (though Redline lists it as working for transmission, too).

I found this on the difference between GL4 and GL5 oil:

The Redline 75W90 NS is GL-5 as you said, but it does NOT contain friction modifiers for the LSD, so not sure if I would use that. I'm also not sure about MTL, MT-90, shockproof thus they are not GL-5 rated.

I wonder if the RedLine 75W90 does contain friction modifiers.

I got my Motul 300 Gear which is GL-4 and GL-5, I'm just wondering if it's ok with the front LSD.

[sujak]

I LOVE motul Gear 300, my gearbox feels awesome.

There are many people using Motul Gear 300 for tens of thousands and miles and have no problem with the LSD's, There's a big vendor that uses it in his personnel car forgot his name.

Also motul states it has additives for differentials, I was just as worried as you, i researched different fluids for roughly 2-3months before my 30k service.