General Automatic transmission question

[DMC3165]

I recently acquired a low mileage 03 Chevy impala. The car is in fantastic shape overall. Some minor issues with the cooling system but other than that it is literally like a brand new 13 year old car.
My question is I'm going through the car and want to change all the fluids. The recommended service interval for this particular transmission is 50,000 miles. The car currently has 41K. There seems to be a lot of mixed opinions on changing the fluid or leaving it alone. Since its under the recommended service interval it should be ok. But I know it was generally used for short trips and up until last week probably never left the Tampa Florida area it's entire life. Fluid seems nice and red and no issues at all. Just like being proactive with maintenance. Thoughts?

[PJ Grady Inc.]

I'd say change it. It's when it smells burnt that you risk finishing it off with a fluid change. If you wait too long you lose that maintenance window that you should still be within.
Rob

[DMC3165]

Thanks Rob. Changing it was my gut instinct. I may let the local Chevy dealer due it. They get $230. For it and they flush out the old stuff rather than just dropping the pan and filter. I always hated servicing automatics myself anyway.

[Farrar]

Received wisdom is that you should change the fluid on schedule, but don't let any shop guy sell you a "flush" unless you've been having problems.

Hm, that reminds me, it's time for my 100,000-mile transmission fluid change ... Thanks!

[DMCVegas]

Received wisdom is that you should change the fluid on schedule, but don't let any shop guy sell you a "flush" unless you've been having problems.

Why wouldn't you want to change out the fluid? I mean, unless it's a car you're trying to unload onto someone, don't ever add any sort of additives, sure. But hydraulic fluid does break down, and given that it is hydroscopic can cause delayed shifting problems as the water content within it is compressible. Just like a brake line.

Now if the fluid is burned like Rob says, yeah, there is a possibility that standard detergents can knock already damaged friction material off. So you're in for an unavoidable rebuild either way.

[Farrar]

Why wouldn't you want to change out the fluid?

Please re-read my post. There's a difference between a change and a flush.

[DMCVegas]

Please re-read my post. There's a difference between a change and a flush.

I give up. How you you change all of the fluid inside of a transmission system without flushing it?

[Michael]

I give up. How you you change all of the fluid inside of a transmission system without flushing it?

The two services are quite different.

One is simply a drain and refill, maybe drop the pan and change the filter if possible. This gets about 80% of the fluid. The other requires fluid or sometimes special cleaner being injected through the cooler lines. This is a debated service that a lot of techs say is not necessary and can damage your transmission.

[DMC3165]

My understanding of a flush was that they run fresh transmission fund through the collateral lines into the unit until all the old stuff was out. Not any sort of detergent or other materials.

I recently spoke to someone about changing the fluid myself and they said to take the cooling lines off the radiator and run the car until fluid stops coming out and that removes about 98% of everything in the transmission. But screw that up and you'll burn up the pump.

It seemed reasonable to let my local Chevrolet dealer due it and not a third party shop. But since I still have a little while to think about it. I'll just run it for a little bit first.

[Farrar]

Thanks, Michael, for explaining the difference.

I'll buzz off now.