Transmission Flush...

boynamedsue · Post by **boynamedsue** » 19 Jan 2010, 16:06

I Have a 98 S70 with almost 300,000 miles on it. The trans fluid has not been changed for quite a while...(about 150,000 miles) I heard somewhere that if you change fluid when its real old, then it can mess up the transmission. Is this true?
Thanks

Post by **polskamafia mjl** » 19 Jan 2010, 16:07

Flushing the trans can mess it up. In your case simply do a series of drain and fills and you will be fine.

boynamedsue · Post by **boynamedsue** » 19 Jan 2010, 18:35

Thanks! Just to clarify, drain and refill then run the engine...repeat?
How many times do you recommend?

Post by **Ozark Lee** » 19 Jan 2010, 19:46

It usually takes three or four iterations - the color will be your guide. When the fluid on the end of the dipstick looks nice and fresh you can call things good.

Even one drain and fill will help things but for the maximum impact getting the fluid to the 90% + entirely fresh level is the best.

...Lee

Post by **bigdaddylee82** » 20 Jan 2010, 14:18

Slight hijack here:

Could one of you explain what's going on to cause a flush of the transmission to "mess it up."

I've recently had my engine/trans out of the car, drained everything, even the torque converter and refilled with O'reilly's house brand bulk trans fluid.

I haven't "flushed" per say, in that the pump, cooler, and pan all have some residual 100K+ mile old trans fluid in them.

Now you guys have got me worried. Am I fretting over nothing?

I swear I'm going to buy a 1983 Chevy pick up or something any shade tree, normal sized, non contortionist mechanic can work on, and can find parts cheap every where

.

- Lee

boynamedsue · Post by **boynamedsue** » 20 Jan 2010, 16:09

What I was told (grain of salt) is that if you have a bunch of miles on a trans. without flushing, it gets used to the old fluid, and if you suddenly replace it, the fluid is too strong for the "old stuff" inside there. I'm not sure if I buy all of that, but thats is what someone told me regarding a thunderbird I had with 280,000 miles on it a while ago.

Post by **polskamafia mjl** » 20 Jan 2010, 18:19

Debris and metal shavings gather up around the seals in the transmission. When you have the trans flushed after a prolonged time of not flushing it, the debris and stuff that was helping the seal gets flushed out and the seals fail causing the trans to fail.

Toplights · Post by **Toplights** » 21 Jan 2010, 03:38

Cant agree that changing the fluid can damage the box,the box is made to live in transmition fluid,getting the wrong grade of fluid is what can do the damage.I have recently changed mine 140,000m,i had a jerk in a change up, it cured that.

Post by **polskamafia mjl** » 21 Jan 2010, 14:50

You misunderstood me, I think. Changing the trans fluid is not only good, it is necessary to do. Flushing the trans is what is dangerous in my humble opinion and I believe most members agree. Drain and fill is the way to go.

Tony Calderone · Post by **Tony Calderone** » 21 Jan 2010, 16:51

just went in to dealer for 82500 mi service and was advised to perform transmission flush, new filter and software upgrade to eliminate hard upshif and downshift from 1st to 2nd and 2nd to 1st will pick up tomorrow with fingers crossed - will let you know - by the way it sound like i am getting ripped off - $1300 for 82500 mile service, trans flush, trans filter, trans software, engine software, engine air filter and front low beam light bulb replacement. Before i complain can anyone give me an opinion about these charges?