Transmission fluid change or flush

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Truluv205

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I have a 2017 expedition limited with 85,000 miles, I haven’t had a transmission fluid change since I’ve owned it, should I get a change or flush.
 

riphip

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Most places will only do a flush, a full change would be great adding a Magnitec filter in the return line.
 

ManUpOrShutUp

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I'm strongly opposed to high mileage flushes after we had one push an aging trans (200k+) to its death, but at 85k I have always gone w/ a flush. Later on I just drain, fill and change the filter.
 

99WhiteC5Coupe

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I have a 2017 expedition limited with 85,000 miles, I haven’t had a transmission fluid change since I’ve owned it, should I get a change or flush.



GM has issued a TSB instructing dealers to NOT flush automatic transmissions (except flushing an external oil cooler for debris after repair), including the six-speed transmissions (which were developed jointly by Ford and GM).

GM also states adding anything other than recommended transmission fluid is considered a contaminate.

MANY dealers push the flush method as it is a huge money maker by them, as opposed to removing the pan and replacing the fluid and filter. Some flush procedures (such as by aftermarket company BG) use a cleaner in the flush, which could be considered a contaminant.
 

JasonH

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You can just drain and fill it. But if you're adamant about cycling out as much of the old fluid as possible, change it a few times after driving it to dilute the old fluid. If it makes you feel any better, I've only drained and filled once in 145,000 miles and have no transmission issues.
 

ExplorerTom

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I’m not sure you can flush it. There’s a thermostat that won’t be open.
 

TobyU

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I have never been a supporter of these flushes and they basically were designed to make it easier for the quick lube places to do a transmission service and charge you more money in the process by marketing it as being better.
You will find that finally people and parts of the industry are coming around to blowing the whistle on this lazy and often harmful procedure.
85k I doubt it's going to do any harm at all but on high mileage ones it can be the straw that breaks the camel's back.
I have seen a handful of cars with high mileage that have never had the transmission fluid touched get flushes and then in just a matter of days to barely over a week have a slipping transmission.
There are those who will say that it was going to happen anyways which is true but it wasn't going to happen then. It might not have happened for years.
Then to top it all off when they don't drop the pan they can't remove all the grit on the magnet that's in so many transmission fans and you're not getting a nice fresh clean filter to replace the old one.
I feel it is always better and safer to do a pan drop and flush the fluid and on the ones that don't have a way to drain the converter, which is most vehicles, you can either pump the fluid out from a transmission cooler line or you can just do the service twice in a fairly short period of time or if it wasn't that bad to begin with it's really no big deal but I would still take that over a flush any day.
 

Brons2

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I just drain and fill, and do it more often, like every 15-17K. The fluid comes out looking about the same as it did going in, which is what I want. If it comes out looking used up, you have a problem.
 

TobyU

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I just drain and fill, and do it more often, like every 15-17K. The fluid comes out looking about the same as it did going in, which is what I want. If it comes out looking used up, you have a problem.
That's probably a little extreme for any type of automatic transmission and probably a waste of fluid.
I think even in the most extreme recommendations they only recommended you change the fluid every 30k.
In fact, there can be a point of diminishing returns with changing automatic transmission fluid especially since so many of them now use a highly friction modified fluid which is slipper when it is new than it is once it wears a little bit and get some clutch lining material into it.

I know cleanliness is a great thing but if you were to do some real world testing of 100 different identical transmissions under the exact same conditions and a third of them you never change the fluid, another third of them you change the fluid every 50 to 70 k and the other third you ran a continual supply of fresh fluid through it or change the fluid every 10K... You just might find you would have more clutch pack and slipping failures from the one with the freshest fluid in it.

We just have to consider that it's like some other things in life, when a little bit is good, it doesn't mean that more more is always better.
Everything in moderation, isn't that what they say??
 
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