I have a 2004 4x4 with 305K on it. Never changed the transmission fluid and I think its slipping a bit.
Beentold that I should not change the fluid because the new fluid would somehow damage something and to just not worry about it.

So OK to change the fluid or not?

 

Well, this question is about like asking somebody which stocks to but - there's a heap of ideas, opinions, and anecdotes you'll hear. My answer - I don't know. But, I've done it at over 130,000 miles on '93 Dakota, no problems. Over 170,000 miles on '06 Camry, no problems. '96 Chevy 1500, transmission burned up in less than 5,000 miles. That's just me anecdotal stories. You have over 305,000 miles??!?!? Wow! I'd say, hey, can't hurt to try. Then, just be ready to rebuild anyway with that many miles, you've done good!

 

I would say change the fluid. With 305K it cant hurt it.

Thanks
Greg
www.motofablifts.com

 

Saying to not change the fluid is the same as saying you can't add any new fluid if it has a leak. I had a Saturn VUE with 5-speed Aisin auto that developed a leak at the cooling lines bracket on the trans. I didn't know it was leaking until it started slipping. It was under warranty, and they fixed the leak, refilled the trans and it was great. It took nearly the whole capacity of fluid, so that basically was a change. About 35,000 miles later I did a 'drain/fill' (pan dump, but this one didn't have a pan - it had a drain plug, and it was fine until I traded it at about 85,000. I have done the 'total fluid exchange' (TFE) as well as pan dump with refill - gets about half the fluid and is adequate for lower-mileage fluid that has not turned dark. The object here is to do it again several times over about a year, and you have then changed almost all the fluid. The TFE is best as it gets it all at one time.
I think what gets people confused is they use the term 'flush' indiscriminately. A trans flush can be done at the time of TFE by adding a can of auto trans flush and running the engine before doing the TFE. I have never done that, and I've never had any problem. I will typically change auto trans fluid on the 50,000 mile mark.
My favorite ATF is Valvoline 'Max Life' which comes in two types that include all specifications, including Toyota, Honda, Ford, etc.

ETA: My newest car is a KIA Sportage, and like many newer vehicles, the trans does not have a dip stick and fluid maintenance is not anticipated until 100,000 miles. So I won't be doing anything to that trans - if it fails, it's under warranty. I'll be trading it in on another one in 2016 if all goes well and they still have a model I like.

 

What I've run into is this: A customer brings their vehicle in for a transmission flush when they start having problems, i.e. "it's slipping." So the mechanic flushes the fluid or even just does a pan drop and filter change. A week later it's back because the transmission finally gave out, and now it's all our fault because we just flushed it. Myself and many other mechanics have been burned by this enough times that customers get the "flushing it will only hurt it" story.

Here's the thing, it won't necessarily hurt it but the odds are, it won't help. If the transmission is slipping, a simple fluid change probably isn't going to be a long term solution. There's a more in depth problem (burned clutches, failed piston seal, etc...) that isn't going to go away. In fact, it may get worse once you remove the fluid that has the friction material from the clutches suspended in it. My rule on it is: I'd rather charge the customer LESS money for transmission diagnosis instead of twice the cost and cross your fingers. That being said.....

Changing the fluid yourself to try and get by or maybe get lucky and have it help is a lot cheaper than a flush at a shop. It might be worth it to drop the pan and replace the filter just to see what happens. Odds are at that many miles if it's slipping, a fluid change won't help, but if the cost on the parts is low enough and you do it yourself, have at it.

 

change the fluid...then right afterward start shopping around asking prices and such for a full rebuild.

TBH I have to say that you got your moneys worth out of that slush-box sir!

 

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