Transmission Fluid

[444]

Have a 1976 280z with a automatic. The car has about 160,000 miles on it. The transmission fluid looks brown as you would expect. I have read where it might not be a good idea to have the fluid changed now, especially if it has never been changed. (which is what I suspect)

 

Would like some opinions of some of you guys, especially if you have changed yours and what the results were afterwards.

 

Thanks

[black gold man]

I changed two auto trans 180,000 miles and one with 56000 miles both work good.

If you change it get proper fluid old dextron fluid.

I bet some trans got wrong fluid because there is some that says for Japanese cars on the label but that is for new cars.

And if you use a sealer on gasket use very little were it doesn't get in the trans.

I hear the fluid filter machine is something to avoid on a old trans.

[hr369]

How does the transmission work overall? does it slip when it downshifts into 2n'd? 

Does reverse make strange noises or slip?

If any slippage, don't change it.

 

Even if you did change the oil and it started slipping, you can pick a used jatco up pretty cheap to free.

If you have to pay someone and can't do it yourself, i'de leave it alone. I never changed mine in 15 years but thats only because i knew

there was a problem with reverse from the day i bought it and it wasn't worth changing.  Reverse finally gave out

but the forward gear clutches were still going strong with that old fluid. It was brown but not a really dark brown.

[Martzedcars]

You guys are unbelieveble...  MAINTENANCE seems unimportant.............

[Chickenman]

I've really put some hard miles some Automatic trannies with Autocross cars and Trailering. Two golden rules with Auto Transmissions. They like clean oil and they like cool oil.

 

Change the ATF ASAP and the filter!!! Burnt ATF can destroy an Auto Tranny. It oxidizes and loses lubrication ability when over heated. Slight burnt smell and brownish tinge is a Red Flag. Black and stinking is too late!!

 

Excess heat ( Towing, Competition or poor maintenance ) just kills regular ATF, and when your oil fails  your Transmission fails as well.

 

The factory oil coolers are seldom adequate. I always add a fairly large Hayden or Trans-Cool  auxiliary cooler in front of the Radiator. That really extends the life of an Auto. PS Pumps also benefit from a small  auxiliary cooler if you Autocross or Track day.

 

Synthetic fluids can withstand a lot more heat before they break down. I use nothing but Synthetic fluid in any Auto Transmission, street or competition. Synthetic ATF has saved me a couple of transmissions that had been incorrectly assembled by " Professional " shops. I've since learned to build my own Auto Trannies for competition and they always get Synthetic now.

 

Amsoil ATF ( available in GM Dexron formulation as well as Ford Mercon ) is VERY good. Not cheap. But really good stuff. It's worth the extra cost in the long run. Even on a used tranny.

[hr369]

You guys are unbelieveble...  MAINTENANCE seems unimportant.............

Yep, especially when the trans is on its way out. Why waste money on new fluid?

[Stanley]

The main problem changing the fluid is about half of it will be in the pan and the rest will stay in the torque converter. However it's easy to get it all out:

   1. jack it up, pull the pan (carefully so the fluid doesn't spill), and remove the fluid, clean or replace the screen and clean the pan, and adjust the bands if they haven't been done recently. Adjusting the bands is way easier than it sounds, but you need a small torque wrench, since it's supposed to be torqued "exactly" what it says in Haynes/Chilton.

   2. Replace the pan and pull the "out" cooler line off the radiator and direct it into a container. Run the engine about 20 seconds and it will pump the fluid out of the torque converter into the container.

   3. Hook the cooler lines back up, and put a little less trans fluid than book says. Then start the car and let it idle in drive or reverse for about 30 seconds until the torque converter fills up. You can't drive until it fills up. Then put a little more fluid to get it the right level on the stick. 

 

While you're at it, check the little hose from the hard vacuum line that connects to the trans modulator. Mine was old and fell off frequently, resulting in crappy trans performance. Put a new vac hose, now it's fine. I run synthetic ATF (145 K miles on the car) and the trans feels great.

 

Edit: Use jackstands or preferably ramps for safety !

Edited December 21, 2015 by Stanley