Graunch?
do you need antibiotics for that?

 

Just wanted to update you guys on the MT-LV fluid in my car.
It got hot here recently (110 degrees+) and the fluid continues to perform well. I have about 13-14k miles on it now, and it still shifts great.
Still shifts better hot than cold, even with this low viscosity fluid and the AZ heat.

Like I said, the bearings and the gears might not be OK with this long term, but the syncros certainly seem happy.

 

Are you doing any competition, track, or autox use?

 

No, street only. In competition use I would definitely use something else. So far so good, even in high (ambient) temps. Even at high temps, it never gets that notchy feel that "too-thin for the application" oil gets.

 

I hear Redline is good stuff. I use Eneos. It's awesome for the cruising I do. I think Charles from BHR liked it a lot.

 

Royal purple is what I have in my trans. I like it. It shifts nice and I find my cup holders don't get warm anymore.

 

A lot of people ended up with bad synchros with RP, never been a fan of anything they offer and never tried it myself

was talking to a guy that specializes in rebuilding these transmissions for racing and he’ll only warranty the Ford Motorcraft XT-M5-QS oil.

 

Rp is the best I could find local at the time. What do you recommend for diff team?

 

I have had a bad experience with Ford Motorcraft XT-M5-QS, but also I am the only person that seems to have issues with it.

Had it in my 8 for like a year, daily driven with about 2~3 AutoX events. It started to get notchy towards the end, and I ground my 2nd gear twice with the clutch all the way in. When I changed out the fluid, it was pitch black and my buddy noted a burnt smell as well when we were changing it. I changed to Motul Gear 300 and it was pretty good.

I used Motul Gear 300 LS in the diff, though supposedly the standard Gear 300 is fine as well since it meets both GL-4 and GL-5, and the LS diff fluid is supposedly more designed for clutch-type LSD.

 

Anyhoo ..........getting the mt-lv thread back on track ........................ My experience matches that of Kevin . This oil is like magic. Would recommend it to anyone having any kind of shifting issue with a street driven 8.

 

you don’t need LS fluid in this differential. If you did, Mazda would tell you. They don’t. It’s not a clutch type.

pretty much any standard 75W90 GL5 gear oil is ok for the differential on the street.

.

 

i am also having issues with Ford Motorcraft XT-M5-QS. Trans shifted well prior. I've missed 2nd upshifting at a couple autocrosses, which is extremely rare for me, and doing slow deliberate downshifts on a road course resulted in grinds. never had those issues with MT90. i think i will go back to redline and assess.

 

I had similar issues with Motorcraft on my S2. Motul DCTF was significantly better. New trans has OEM fluid in it and it's utterly useless, so I'm likely to try the Redline as well. Thanks for the info guys!

 

I tried the Ford fluid and was rarely able to get enough heat in the transmission fluid to have good shifting results. My car hasn’t seen a track yet with me behind the wheel. Much better shifting with the Redline fluid. Shift to second gear with the Ford fluid was an exercise in patience. Don’t have that with the Redline.

 

I will add this also. I just got my other RX8 running, a 2007 with the original trans at 186,000 miles, when I put the car away the tranny had rough synchros, (grinding) in 2nd and 5th. I did not think the tranny would last too long, since the shifting really sucked. I put the MTLV in and immediately second was fine, I could upshift as quickly as needed, which is quick, with a RB light flywheel, to try to be smooth. 5th still grinds at the moment, but only on downshifts, and only when cold. When warm, there is no abnormal behavior. In the original tranny (early s2 in a 2004) I used this in, the shifting has actually gotten better over time, maybe because the fluid has thinned a bit, or maybe because the synchros have "relapped" to a certain extent, I don't know. So far a great result. I would love to see someone use this at a track day, to see if it holds up as well as it does on the street. I think I am approaching 40k on the first fill of MTLV. I will change it soon, and see if any difference is noted with fresh fill.

 

I have just over 5k miles with MT-LV on the second rx8 with the s1 box, and the 5th gear cold downshift grind is gone. All shifts seem to be improving, and rev match on upshift is easy even with RB flywheel. This on a s1 box with over 190,000 miles on it. I noticed on the other 8 (with s2 box) the shifting improved over time, I thought maybe it was an illusion, or viscosity change after so many miles, etc, but it seems like it helps weak synchros the more miles stack up. I would like to hear if others noticed same.

 

Just saw this. This is interesting. So maybe we BC folks just have bad Fix Or Repair Daily fluids around here? Different formula for Canada or something?

Redline is generally regarded as good stuff but my experience with it is very limited. I had good results with Amsoil and Motul. I used Amsoil in my Accord(Manual Synchromesh Transmission Fluid) in Alberta and now Camaro(Signature Multi-ATF, and yes it's a manual trans, TR-6060 is just a little weird like that), and Motul in my RX-8(Gear 300) and now my Mazda3(Motyl Gear, which is semi-synthetic but it's good enough for a family car like that).

 

ditto . I had actually forgotten I even had shifting issues in both my 8s before I put the MT-LV in there.

 

I’ve got about 10,000 km on the Redline fluid and no complaints. 2nd is minimally notchy when cold but, this doesn’t last long even at -10 C°.

 

I did the Motul DCTF again in my S2 instead of the factory fill and it completely fixed my "doesn't want to shift when it's cold" issues.

 

^^why would you use DCTF fluid?

.

 

Most DCT fluids, if not all, are of GL4 and friction modified for synchronized gearing.

 

A quick update:

On the blue RX8 that now has 210k miles on the original 6MT, the 5th gear grind is still gone when tranny is cold. It dipped into the 20s here and still have excellent shifting hot or cold. Over time just like in my other RX8 trans, the shifting actually improves with time. 25k miles now on this fill in a 210k mile box.

Again,

I tried Motul 300v
Redline MTL
Redline MT-90
Ford XT-QS (or whatever)


And I think another oil I can't remember, and this has been by far the best.

 

Update,

First drain on the mt-lv fluid at 45k miles. Shift quality had degraded slightly over the last 5k or so in the 230k mile plus s1 box. In the future I will drain this at 35-40k. The new fill brought back the smoothness completely. Magic.
With the old fluid, shifting felt more notchy and mechanical, but shift speed and synchro action was not changed. Still could not beat the synchro, hot or cold, at any rpm. I will send off a sample for UOA for kicks and will post it here.

The magnet had low debris. The oil itself still smelled new and was still clear.

 

Watching. I filled mine with Amsoil about a year ago, and sixth gear synchro, of all gears, complains if I don't rev match it from above (bizarre behavior). I'll be changing fluids before next season for sure.