So I have a dilemma with my transmission. The fluid is nasty and burnt, but the trans has over 140k miles on it. Should I just drive till it finally gives out? I was told not to flush it because new fluid would "wipe it out".

95 3.4L Auto

 

With that many miles, I flush could clean out most of the deposits that are keeping things together. I would at minimum change the fluid and if you could find another trans for a decent price, try the flush as well. My trans gets flushed every 30k to make sure I always have decent fluid and no harmful build up.

 

The transmission place I took it to said not to even change/flush the fluid. :\

 

Thats a new one on me. I have never heard that old nasty tranny fluid could be helping a transmission in any way shape or form. I would love to hear that explaination. I have known of a few places that used to try changing the fluids or "flushing the systems" even on cars we knew the clutchs where fried on. I think they wanted to make it look like we tried something before we tore into it.

 

I've heard switching to synthetic oils can dislodge carbon deposits that are actually holding back leaky gaskets, but as far as I know, new fluid will not hurt a transmission to my knowledge.

 

Ok, here it is... With the old fluid in the trans, also comes grit and grime that can be embedded into the surfaces of the clutches. Keep in mind that Jordan's fluid is way past the simple "broken down" stage. Now replace that old fluid with shiny new stuff, which will be very high in detergents as compared to the old fluid. The new fluid will start to clean out deposit buildups inside, including the build up of grit in the clutches. Grit equals traction, and if that's all that was keeping those old worn clutches holding, slippage could occur. It's not that the old fluid is helping, but a chance that the new fluid could hurt.