Charley Hoyt

I have been tracking and autocrossing my car for a couple of years now...So I thought (at 24k miles)it would be a good idea to change all of the fluids. The shop told me that the transmission fluid was still in great shape and had no issues. So you should be fine without changing.

Mark VerMurlen

I've changed my manual transmission fluid twice now. I changed it after about 2,000 miles and then earlier this winter which was 2 years after its first changed. The first change had some very fine metal in the fluid which I attribute to the initial gear wear in. So I was happy to get it out of there. May not make any difference, but it can't hurt to get it out of there. I autocross my car a few times a year and have it on the track once a year, so I prefer to change the transmission and differential fluids periodically.

The manual transmission does use Dextron III ATF. I chose to use a fully synthetic ATF equivalent from Mobil 1. You'll need a fluid pump to pump the new ATF up into the transmission from below the car. It's not hard to do, but it can be a little messy. Its full when fluid starts coming out of the fill hole.

If you're going to change the transmission fluid, you might as well change the differential gear lube as well. I chose Mobil 1 75W-90 full synthetic gear lube. There's enough room to squeeze the gear lube from the bottle into the differential without a pump with a short section of tubing.

- Mark

Boomer111

I have always changed my manual transmission oil at 45,000, using snythic fluid.

LS WON

Had my 2005 4 spd. auto trans fluid changed at 34,000 to Amsoil. Mechanic showed me magnet and inside the pan. Wasn't that bad or dirty at all.
Didn't notice any difference on this auto trans in shifting or any difference at all.

On my other 5 spd. manual car I switched from regular factory fluid to Redline and then to Amsoil and yes I sure did feel the difference between regular factory fluid and both synthetics. Shifting was alot smoother with easier engagement.

jsims002

I changed the MTF in my 94 C4 that has a ZF6 a couple months ago. The fluid that came out was still clear but now I have peace of mind, I didn't know what 16 year old fluid was lurking in there and now I do.

I used Pennzoil synchromesh MTF. Remember, if you do it, make sure you take the fill plug out first!!!!!

C66 Racing

I had the factory fill transmisson fluid in my 06 CTS-V (Tremec 6 spd manual) changed out at about 10k miles and the fluid had already sheared low out of grade, a loss of about 40% of the original viscosity.
So while the fluid might not get dirty from combustion byproducts like engine oil does, still good reasons to change it out.

As mentioned above, the GM spec for their manual tranny's is for an ATF. The fluid I use in my 02 Z06 track day car and the one AMSOIL recommends for the C6:
AMSOIL Torque-Drive Synthetic Transmission Fluid (Product Code ATD1G)

Wayne O

It's exceedingly simple to do. It helps if you have access to a lift but if you can get your car in the air you can do it in your garage as well (I've done it several times). Here's an old link that may help:

http://forums.corvetteforum.com/show...ion+oil+change

Always make sure you open the fill-plug before you drain out the fluid. Not only does it promote drainage but you don't want to drain the fluid and then find out you can't fill it back up. Warm up the fluid a bit first. Good luck.

I track my car a lot...I change the transmission fluid at least once a year. I use Royal Purple Sychromax.

corvet786c

Thanks for the replies, I will go ahead and change it soon.

Dale_K

I have a 2005 and it came with the Dexron III sticker. From new it was sort of stiff, especially in cold weather. GM no longer recommends Dexron III - they have a new manual transmission lubricant. I don't remember when the change took place but it was quite a while ago.

I bought 4 qts of the new GM manual transmission lubricant (that's what it's called) and had the local lube place change it. You need a pump to get the new fluid in because the fill plug is up against the floor. I did it at 5 years and 37k miles. The new GM fluid made a pretty big difference in the quality of the shifts. It's not nearly as stiff. The fluid cost about $50 after shipping and I think it was worthwhile. I didn't do it because I was worried about wearing out the transmission - I think you could go 100k on the factory fill - but the new fluid improved the shifting so much that it was worth it.

gunterwalker

I think its a bad idea. Just my opinion. Do what you want. As for the clutch fluid I don't mess with that either. I saw the ranger method but I'll just leave as is. I have changed trans. fluid only twice in my life and after both time the trans had issues around 5k miles after the change. I didn't do the change. The trans shop I used to fix them told me that changing it can cause the shavings to get into the gears and cause issues. Both these were autos with around 50k-75k on them. One was a truck and one was a SUV, both GM. Good luck.

LS WON

Same situation here with 2005 4 spd. auto which they now use Dex 6. I put in Amsoil but I do not notice any difference in shifting. I am sure I would feel the difference it it were a manual like my other car where I could tell the difference between factory, Redline and Amsoil. I had rear end fluids changed also in both cars and can't tell a difference one with Amsoil and the other with Redline.

LS WON

I have had manual trans and rear ends changed a few times using Redline. However I didn't do the change myself. I let the shop do it as in this case it gets real messy when you have to remove the rear end cap and gasket.

ALLEGRO

Mark VerMurlen

There is no need to remove the rear end cap when replacing the rear end fluid. There are simple drain and fill plugs. Don't let anyone pull the cap to replace the fluid.

- Mark

LS WON

Not to worry this is not on a Corvette but on a solid rear axle car.

corvet786c

Thanks for all the replies. I just changed the fluid myself yesterday. I am glad I did. When it came out it looked really lite red, not bold red like in the bottles. I went ahead and bought the GM Specified stuff Part #88861800. By the way a real messy job, but saved what about $80.00 from the dealer. This is what I like to hear. Anyway, didn't notice a huge diffrence in shifting like everyone says, but some. I have peace of mind now the the new stuff is in there and all is well now.

C4RACER

Good job!! I changed mine with the GM spec lube as well at 45K miles, and also changed the diff fluid at the same time to Amsoil synthetic. Can't hurt to swap it out every 40-50K miles, IMO.

Thunder22

i was at the stealer having the diff fluid changed under warranty and the service advisor recommended changing the tranny fluid in my mn6 '08 c6 coupe with 12k miles on it. granted the car is 3 years old but with only 12k miles on it i passed. he said that "these cars are hard on the transmissions" as the reason why. ive never changed it out with that few miles on a tranny in any car ive owned. imwas surprisedmthat her recommended it