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How often to change Auto tranny fluid?

19K views 13 replies 9 participants last post by  thecorvettemechanic 
#1 ·
Curious how often you all change your auto tranny fluid? Am I ok with once a year? I put maybe 8,000 miles on the Vette each year, I wouldn't say I horse the car much. I change my engine oil every 3,000 miles, even though I know the oil can last much longer. I guess it just gives me something to do on the car on a more regular intervals!
 
#2 ·
The recommended automatic transmission fluid change interval is 50,000 miles.
 
#6 ·
Changing the fluid is such a PITA, why even bother with it on such a regular basis if you don't need to?
 
#8 ·
HI there,

The key is driving. If you reference your owners manual on the 2006, they actually say that you shouldnt have to. This is because Dexron 6 is a semisynthetic fluid and doesnt oxidize like the older stuff does.

This being said, I recommend to have the fluid COLOR AND CONTAMINATION checked.

This means, removing the drain plug, dripping a few drops onto a white piece of paper and looking at it. All Dexron fluids will turn brown over time as the fluid ages because the dye wears out. That does NOT mean it needs changing. If I see any heavy particles in the fluid, is when I recommend changing it. Thats because the fluid suspends contaminants and these need to be removed.

To Drain and fill the 6L80 in your car, its not easy. The fill plug is in the top of the case and the actual level plug looks like the drain plug on the transmission pan.

I would suggest, if its not driven agressively, not to worry about it. If you have gone 5 years without a change, it certainly would not hurt it, but its not necessary.

Allthebest, TCM
 
#11 ·
I dont reccomend power flushing. Half the places that have that machine charge and arm and leg to do it then theres finding someone that can actually run the machine.The flush is a closed loop setup.The sediment and dirt in the pan gets blown into the mix.Which gets passed through all the internals of the valve body.The particulate matter can get lodged in the body and cause failure in the trans.Plus if the idiot running the machine sets the wrong setting at the wrong pressure you can even blow seals. Best way I know of is 50k and get the pan dropped and the trans filter replaced. This way the pan can be washed and your using a new filter with fresh fluid.Kinda like changing your oil you dont reuse the old filter. Just my opinion its the way I've done it for years.
 
#12 ·
HI there,

The truth behind accurate machine flushing process is HOW does it flush. Some machines are ridiculous, others are very effective.

Most quality flush machines use the pressure produced by the internal transmission pump to push the old fluid into the machine. This pressure exerts force on a bladder within the machine, to force new fluid INTO the transmission.

These pressures at the connections for the transmission cooler simply take the filtered fluid out and puts fresh fluid into the lubrication circuit.

One of my questions would be, 'how does the machine work?"

A filter change is always recommended to determine how bad the transmission wear is, because you can split the filter apart and check for contaminants that are caught in it.

Allthebest, tcm
 
#14 ·
HI there,

I dont agree with that for only one reason.

A torque converter will hold about 1/3-1/2 of the total transmission fluid capacity. When a transmission fluid pan is removed, you are draining what is there, but not what is retained within the torque converter, transmission lines and control valve body.

Here is one example:

2008 Corvette with a 6L80 transmission.

Specifications for fluid capacity when removing the transmission pan/filter: 6.7 quarts

Specification for a complete transmission overhaul: 11.3 quarts

Total fluid capacity for the transmission: 13.2 quarts

I think that so many customers are given the "selling/marketing speech" about flushing, what it does or does not do and it confuses people.

Its unfortunate that the only people who suffer, is the customer.

Allthebest, tcm
 
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