Quote:
Originally Posted by oldskewel
Counterpoint ...
Bought my '01 3.0i with ~168k miles, whose owners religiously followed the (lack of) scheduled ATF changes. Yes, original fluid.
I very carefully researched this, and ended up doing 3x drain and fills with DEXRON VI, including two new filters, over the next ~4k miles. Significant improvement in how smoothly and quickly it shifts.
Still running fine at 178k+ miles now.
At 120k you are pretty low still. If you can do the changes carefully or get a good mechanic to do it, I'd highly recommend it. I'd definitely not do a full, powered flush, or take it to somewhere that does not know what they're doing, or do it myself without figuring things out carefully.
From reading many many threads on this list, it seems pretty common for AT failure to follow soon after AT fluid servicing. So yes, it's something that can be screwed up.
Another general tip is that the ZF transmissions use different fluid from these GMs. So to keep it simple, I learned to just ignore anything on the ZF AT's.
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I think a lot of those failures is due to not following the proper procedure to fill the trans. The temperature of the ATF in the trans can't be more than 40C, but when people change the ATF they drive the X until it is at operating temperature. If the engine temp is around 195F or 90C that temp in the ATF is also at 90C which is way over what is recommended.
You can drive it until it is hot, drain the ATF, but wait overnight until the remaining fluid in the trans and torque converter have a chance to cool down to a temp below 40C or 104F before refilling the trans. Hot ATF expands and if the ATF is more than 40C, the fluid would have expanded so that when it has a chance to cool down, the trans will be low since the ATF will have contracted.