: Transmission Fuild Synthetic or not?



homer403
01-26-05, 07:19 PM
Ok, just had my first transmission fuild change and it cost me $67.33, but my question is should the fuild be synthetic or not.... the bill only say the used Mobile ATF MP... want to know if the used the right oil. HELP :hmm:

6104696
01-26-05, 07:41 PM
The factory uses plain old dexron III, which is what I used. Rick had tried the synth, but then I think he was going to swap back in some conventional to see if there were any cold shifting differences. Rick, did you ever try that?

At 68 bucks they gave you the plain stuff. Synthetic would have cost you more (though I think it cost me $10 to do mine at home:) , but I did have quite a mess to clean up.)

Doug

homer403
01-26-05, 07:46 PM
Doug… let me show my ignorance :hmm: … but if they used Mobile ATF, as in automatic transmission fluid… is this right???

RobzBLKV
01-26-05, 08:19 PM
ATF is automatic transmission fluid and most modern manual transmissions use it. Don't ask me why or what the difference is.

6104696
01-26-05, 09:58 PM
ATF is automatic transmission fluid and most modern manual transmissions use it. Don't ask me why or what the difference is.

yep. You got the right fluid, homer. "Dexron III" is probably the most common ATF. On the side of your transmission is a big orange label that says "DEXRON III ONLY" or some such thing. "Type F" used to be spec'd for Ford automatic transmissions. It's been about 20 years since I had a Ford auto, but I think that they have switched to Dexron III, too. My mustangs have all, I think, spec'd Dexron III for their T-5 manual transmissions.....

the ATF is much lower in viscosity than the gear oil that used to be spec'd for manual transmissions. I can only guess (and I am sure that someone will correct me here) is that as the synchros started to be more numerous and more developed (and maybe smaller), it was determined that the thinner fluid allowed smoother shifts but still gave good lubrication.

Doug

StealthV
01-27-05, 12:32 AM
Right now I've got "regular" ATF with the "GM Goodwrench" label on it in the V.

As the weather has gotten colder this winter, it doesn't shift as nice with this fluid as it did with the Mobil1 synthetic. Once the transmission warms up above 80 degrees on the morning commute, the difference between the two fluids is imperceptible.

peccles
01-27-05, 02:28 PM
Like synthetic oil, synthetic ATF will flow better when cold and protect better at higher temperatures. The latter becomes more useful if you take your CTS-V on the track.