I have a 98 S70 approaching 230k the tranny shifts out with no problems. i have no history and was debating whether I should change the fluid, flush the fluid, or leave it be. Thanks for the input.

 

with high mileage transmissions it's better if you change the fluid. Same as high mileage engines and oil, debris fills in worn spots/crevasses through out the engine and when you go to a thinner oil or change from natural to synthetic you loosen up that debris. My dad knows countless mechanics and has been told on several occasions that they have seen people get a transmission flush on a high mileage tranny, just to have it crap out two months later.

 

You don't need a flush, just drain it once or twice like an oil change. it's called a drain and fill. Takes 3.5 quarts of Dexron III. It's the additive packages that need replenishment, and the friction modifiers.

Yes, refilling with trans fluid is always advised, no matter the myths out there.

 

Of course use transmission fluid. If you got the impression that I was advising to use something else, that's not what I meant. It is just my understanding that you are not supposed to do a "flush" on a high mileage tranny and just simply change the fluid.

 

I have 96 850 n/a 200k and never did flush or refill. I was told not to play with it now. It works perfectly and I hope it stays that way.

 

Glad that works for you. And if you are comfortable with that schedule they stick with it.

For me, It's simply not advised to keep any fluid in there for the life of the car. They should be replenished.

I treat trans oil sort of like engine oil. They break down and oxidize and need replenishment.

Every year I do drain and fills on my three Volvos S-70,S60 and XC90, Ford Escape and Acura RL. All have significant mileage on them except the XC which only has like 30K on it.

All trans appear to be very smooth still. The S-70 has 175K and still shifts very smoothly.

 

Thanks for the responses. Does anyone recommend one brand of ATF over another? I was considering Redline.

 

200K is a lot of miles on any fluid. Do what you want but I would change that out if I were you.

 

You can use any off the shelf transmission oil to Dexron III standards or above.