pvknight

Hi all,

I have a 1998 Coupe. Just changed the 6-speed manual transmission fluid this weekend, only 42k on the car, not driven much by the previous owner. I went with Vavoline ATF DEX/MERC. I used the same stuff on my last corvette without issue.

After the fluid change I noticed:
1) no improvement in shift quality
2) a noisy throwout bearing sound ~1500rpm
3) a rough clutch engagement at higher rpm shifts (4000+)

Has anybody else had experience with this fluid? Recommended alternatives?

Thanks,
-Brian

RaW Z06

Drain that crap out of your transmission.

Go to your Local GM dealer and Purchase 4 qts of Manual Transmission Fluid (GM # 88861800)

This is the correct fluid for your tranny.

injun.724

Use Pennzoil Synchromesh. Excellent shifting with no notchiness.

baxsom

manual calls for ATF in the MN6. did something change? amsoil TQD is also an excellent alternative

pickleseimer

Had the same issue after using Royal Purple Max ATF. Shift into third would catch a tooth or two while cold but went away after a few miles.

Called Tremec last week, talked to their rep (named Rob), and asked what should be used in my '01 MN6. He said Mobil 1 Synthetic ATF is what Tremec recommends, and that is also good for the paper blocker ring versions as well (surprising given all the internet smack downs on synthetic ATF and paper blockers).

Drained the RP - only had 200 miles on it - installed the Mobil 1, and the difference is remarkable - smooth shifts and no synchro issues.

C66 Racing

Alternative I've been using in my track day car for years with no problems:
AMSOIL Torque-Drive Synthetic Transmission Fluid (Product Code ATD1G)

johnson-rod

pvknight

Thanks for all the responses, it's very helpful in addition to all the threads I've searched and read.

Noise:
I'm not experiencing a grind going into any gears, but rather a "growl" from the tunnel/shifter area as I accelerate past 1400-1600rpms. Very noticeable when cold, but it goes away once the car (transmission) warms up. Weird.

Feel:
Here's a question. When you guys depress the clutch pedal to shift at RPM's above 3500, do you "FEEL" the engine spinning/working through the pedal as you engage the clutch?

Other cars I've driven had pretty "harsh" clutch feel in the upper revs, but I remember the vettes had a very SMOOTH and ISOLATED feel regardless of how hard the engine was working.

-Brian

RaW Z06

The book Calls for Dexron III

Dexron IV is backwards compatible for Auto's but not for Manual's.

GM specifically recommends Manual Transmission Fluid #88861800

pvknight

Good info. Though the dealer here seems to have Dexron III ATF listed for my '98 6-speed, but the 88861800 for the newer C6 vettes - ?

Maybe the Z06 trannies can take the MT fluid? Seems the 98-00 transmissions are more picky.

ps enjoying the Ti's VERY much

RedZMonte

I swapped my stock fluid out for Valvoline Dex III without any issues. shifts just like stock. I didnt notice any difference one way or another other, the stock fluid was 30K miles old on a '04 and dirty as heck. Dex VI is not compatible with the 6spds, must be Dex III or GM MTF, I read that the GM MTF is rebottled GM DEX III ATF. I have never tried GM SyncroMesh or Pensoil SyncroMesh... but i have heard of other car guys out there using GM Syncromesh in their cars (Honda, subaru, ect..) with good results.

S

pvknight

seriously??

I used Valvoline DexIII a few years ago on my '00 FRC, and it was great. Smoother, quieter shifting and driving.

But, I think Valvoline has changed it to a DEX/MERC hybrid now, so that they can sell to the Ford guys too. Seems the quality was compromised...

and, GM DexIII is hard to come by at the dealers around here...

Cybermind

The difference in shift quality was remarkable when I changed my OEM tranny fluid to Mobil 1 Synthetic ATF. I highly recommend it.

leadfoot4

Not trying to hijack the thread, but I changed my tranny fluid yesterday, for the second time, in my '01 coupe. The first time I changed it, I looked somewhere or other, and based on what I found, I think I bought 5 quarts of tranny fluid. I drained it through the drain plug, refilled it until it was almost dripping out of the fill hole, but had 2 quarts left over.

That was around 2004, and I had a couple changes occur in my life, and along the way, I had to get rid of a lot of "extra stuff", including the extra bottles of Dex III fluid. I admit that my memory isn't all that great, so when I ordered fluid again, I didn't remember exactly what I previously used, and what I had to get rid of, so I once again ordered what the reference material said, 5 quarts.

Once again, I have 2 quarts left over. Anybody know what's up with this? I understand that in an automatic tranny, the torque converter and cooling lines retain a certain amount of fluid, so there's a "dry fill" fluid capacity, as well as a "filter change" fluid capacity. I've never seen a manual tranny that "holds fluid"....

Oldvetter

I use Amsoil TOD (Torque Drive), it is about $50 a gallon.

DO NOT use Mobil 1 ATF with 1997-2000 C5s, due to their paper blocker rings. I did and after 50,000 miles my trans started grinding going into 5th and 6th gears. A change to Amsoil Torque Drive stopped it immediately !

johnson-rod

The first change I went with autozone DextronIII and it didn't feel any better than the 10 year old DextronIII from GM. The next year I went with Amsoil Torque Drive and it was like 'budda'.

leadfoot4

Probably because the Autozone Dex III isn't a synthetic fluid, whereas the Amsoil is.....



FWIW, I've use Red Line's synthetic Dex III.

baxsom

My manual on page 7-19 specifically says automatic transmission fluid for both automatic and manual transmissions. What is the difference between GM MTF and Dexron III?

RaW Z06

2007 GM TSB#04-07-30-037D clearly states, "Any vehicle that previously required DEXRONŽ-III for a manual transmission or transfer case should now use P/N 88861800".


Hope this helps

pvknight

Thanks, very helpful! Changed to the MT this weekend