Transmission Filter or Flush

[sawdust2]

My Grand Prix GT with a 3.8 motor, has 107,000 miles. I don't know if the filter has ever been changed. Which is best, drop the pan and install a new filter and oil, or have it flushed? It shifts just fine with no problems at this time.

[BNaylor]

With your mileage I would be careful about flushing. Just do a pan drop consisting of ATF (Dextron-III) and a screen filter. You will need around 7.5 quarts of ATF and I would stay with the AC Delco screen filter, part #TF304 (25313825). The pan gasket can be re-used. Pan bolt torque 10 ft-lbs.

[guitarfish]

I do a filter/fluid change about every 30K. Takes about an hour. I've always used the Fram kit FV1129. There's a small ring-sized grommet included - I seldom replace it. Kindof a pain in the butt to remove, you have to pry it out with a screwdriver.

[richtazz]

I 100% agree with bnaylor on this. With any trans over 80k that has never had a trans flush, it is a BAD idea to do a flush. Only replace the filter and what fluid is in the pan when you drop it. A trans flush at your mileage will almost certainly cause major problems due to the new fluid being grippier than the old. It most often shocks the clutch friction plates, shearing them from their backing plates, necessitating a complete rebuid. Trans flushes as regular maintenance are not bad, although I feel they are totally unnecessary and a waste of money if the trans filter is serviced as it should be (every 36k to 50k depending on driving habits).

[MT-2500]

Originally Posted by sawdust2

My Grand Prix GT with a 3.8 motor, has 107,000 miles. I don't know if the filter has ever been changed. Which is best, drop the pan and install a new filter and oil, or have it flushed? It shifts just fine with no problems at this time.

Flushing has killed a lot of transmissions.
Just new filter and new fluid to fill it back up is a lot safer and better.
And no dope or additives.

[rubberman]

Originally Posted by MT-2500

And no dope or additives.

so no Seafoam TransTune? i used some on my tranny when i started getting the hard shifting/whining when i installed my aftermarket PCM. but when switching back tothe stock PCM it quit.


also when changing tranny fluid/filter, i was taught way back when to drain the fluid in the pan plus briefly go thru each gear to remove the extra fluid in each gear. So really all we need to do i refill the fluid that we dump out in the pan? any tips for pulling the pan and not spilling fluid over myself or floor? on previous vehicles, i installed a drain plug on the first tranny fluid change to make it easier next time.

[MT-2500]

Originally Posted by rubberman

so no Seafoam TransTune? i used some on my tranny when i started getting the hard shifting/whining when i installed my aftermarket PCM. but when switching back tothe stock PCM it quit.


also when changing tranny fluid/filter, i was taught way back when to drain the fluid in the pan plus briefly go thru each gear to remove the extra fluid in each gear. So really all we need to do i refill the fluid that we dump out in the pan? any tips for pulling the pan and not spilling fluid over myself or floor? on previous vehicles, i installed a drain plug on the first tranny fluid change to make it easier next time.

Just like a flush additives can do more harm than good.

On draining get the biggest pan you can.
I use the end cut off of a 55 gallon drum.
When dropping pan go easy and drop one corner first.
Drain plug is optional. And is handy for just draining fluid.
But the pan need to come off to change filter.
Good Luck
MT