Should I Change My ATF??

[Green LT1]

I have a 1996 LT1 with 41,000 miles. It has never seen a race track, and is driven conservatively (most of the time). Every once in a while I will give it a little workout, but I never do burnouts. I have checked the ATF, and it looks and smells good as new. The transmission works flawlessly. The owners manual says it should not need to be changed for 100,000 miles under normal use. I have seen several threads indicating that the ATF should not be changed/flushed once the car has higher miles, as that can lead to transmission failure. That leads to my question - should I go ahead and change the ATF and filter now, as a preventative measure? Any thoughts on this would be appreciated. Thanks!

 

[Hrtbeat1]

Maybe Rain will chime in. I helped him change his fluid in his '96 a while back. Of course he now mostly drives his C5 but he still has the '96. I'm sure I would have heard if he had any ill effects.

 

[Ken]

How often depends on how the vehicle is driven. For some vehicles, this might be every 30,000 miles or every 2 years.

The harder the transmission works, the hotter the fluid runs. The life of the fluid drops quickly once its temperature gets up above about 200° F.

ATF can also become contaminated with normal wear particles from the clutch plates, bushings and gears. A clean filter will trap most of this debris before it can cause problems.

 

[Vettefan87]

With those kind of miles, you should be able to get most of the crud out with just dropping the pan, replacing the filter, and filling it full. I did have a powerflush done, and the mechanic said he did get a lot of crud out. Dropping the pan is a lot cheaper then having a powerflush done.

 

[DAVZKAR]

I changed mine at around 75 grand no problems now I have 136 K runs great. Most horror stories happen to a trans that are time bombs anyway. Fresh fluid and they can't take the extra pressure and strain.

 

[MPoore]

Get it changed now or NEVER change it. As much as I hate to turn over a vehicle to a shop, the flush much better. You only get half the fluid out when dropping the pan. The reason I say now or never is because the longer you wait the more likely you are to have a problem as a result of the fluid change. The flush has a tendency to dislodge crud that can block passages and cause a failure. This is by no means scientific, but from experience I would say that if you get it flushed before 60k there is no chance of creating a problem. After 60k, I would say run it 'till it breaks. Now that's not to say every vehicle getting a first flush after 60k will have problems. As a matter of fact, the risk is still small like maybe one in ten. But, the chances are better that you could do nothing and your transmission last 150k.

Mike

 

[Edmond]

I didn't change mine until it hit the 80K mark. I just dropped the pan and put in new fluid with a new filter. It only took a couple hours to do. You can do it yourself, I have on a couple of cars, but it's easier having someone else there to help.

 

[Vettefan87]

I don't know about the LT1's but I know that the L98 verts have that xbrace that also has to come off. That thing is a real PITA to get aligned back up with the bolt holes, sometimes.

 

[jmccloud]

Trans fluid

The power flush gives a better fluid exchange but drop the pan once and you'll use that method. Most of the crud is stuck to the pan and the magnet inside. Also, you get to change the filter screen with the pan off. Perhaps alternating or combining the two methods would work best.
I have a 91 Buick with 189,000 miles on the trans and I drop the pan every 2 years. Its 3.8L is no Corvette engine but it's strong enough to lay a lot of rubber and pull very hard into 3rd gear at 84.

 

[Green LT1]

Thank you all very much for your input on this. I think I will buy a filter/gasket set, drop the pan myself, and clean everything up really carefully. I will top off the transmission with Dextron, making sure that I don't over-fill it. I have done this before on other cars when I was younger, so I should be fine. Are there any loaded springs, special gaskets or other things to look out for when removing and replacing the filter assembly? Thanks again!

 

[Hrtbeat1]

Are there any loaded springs, special gaskets or other things to look out for when removing and replacing the filter assembly? Thanks again!

One thing I ran into on Rain's car .... the gasket for the filter is a real PITA. The older 700R4's used a rubber gasket the newer 4L60E use the same but it has a metal ring also. It makes for a real tight fit, and a pain to remove. Make sure you get the old gasket out of the bore where the filter connects, when I changed the fluid in mine the first time I found two gaskets up in the bore ... probabally why the filter didn't seem like it was seated (visually after removing the pan.)

 

[jmccloud]

Auto Trans Fluid

NAPA sells a really good filter/gasket (as well as a cheaper one to avoid) that has gasket holes slightly smaller than the bolts. That way you can start all the bolts into the gasket and it holds them in place while you start each one into the trans. with your fingers. The metal is aluminum so take care not to cross thread. Once all the bolts are started torque them carefully (I forget the spec but it isn't much). A handy check is that if the gasket starts to 'extrude' or squeeze out, the torque is too high. One hand on a 3/8 drive socket will provide more than enough torque.
The NAPA gasket must be treated with something because I've never had one leak or stick on subsequent changes.
Double agree with the caution on the filter gasket. Don't get two of them in there or the pan won't go on correctly. I use a dental pic and a small bent screwdriver when necessary to get the old one out. One gasket removal usually destroys one pic.
Be sure to pull the magnet off of the pan and wipe it clean. Some magnets are donut shaped, others are square or rectangular. Usually there's a depression in the pan to relocate the magnet.
A lint free cloth is good for the final wipes on the pan before reassembly. Usually a 100% or high content synthetic cloth (like acrylic) in an old undershirt is lint free. Paper towels are 'dirty.'
Good luck.

 

[Edmond]

What I do is clean out the transmission pan with gasoline and also the magnets, then I take compressed air to it to get rid of anything else left in there like lint, etc...

 

[WhalePirot]

What I do is clean out the transmission pan with gasoline and also the magnets, then I take compressed air to it to get rid of anything else left in there like lint, etc...

I prefer brake or carb cleaner to gasoline, which I used to use. Either should leave no residue and may preclude wiping with any rag. I like the powerful spray (which I don't have to touch) and quick evaporation, leaving a rather 'sterile' surface. I finish with compressed air, too.

When you check your tranny fluid level, note the color and the smell. It should be meduim reddish and not smell burned. Knowing the newer fluid's characterisics helps us know when it is in need of change.