Question for the experts: Transmission Flushes: Good or Bad?
Thread Starter
Teching In
Joined: Jul 2005
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Question for the experts: Transmission Flushes: Good or Bad? I've just purchased my new baby: a '98 Trans Am w/ 68k miles and i'd like to take good care of her so.. planning on perfoming the 60k maint. But I had a few q's about the auto transmission flush that was recommended by the GM dealer.
Now, from what ive read on the forum, looks like the service does vary between just doing the pan/filter to doing the pan/filter and the tranny flush with new fluid.. and in-between...
But opinions seem to vary quite widely on the forum..
Right now the fluid is pretty dark, but there are no shifting or slipping problems just nice and responsive shifting. I'd like to keep it that way, so what do the experts think about doing a tranny flush?
Now, from what ive read on the forum, looks like the service does vary between just doing the pan/filter to doing the pan/filter and the tranny flush with new fluid.. and in-between...
But opinions seem to vary quite widely on the forum..
Right now the fluid is pretty dark, but there are no shifting or slipping problems just nice and responsive shifting. I'd like to keep it that way, so what do the experts think about doing a tranny flush?
TECH Enthusiast
Joined: Dec 2002
Posts: 736
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From: Chattanooga,TN
Well I'm no expert but when you just drain the fluid and change the filter you don't change/get all of the fluid. There is a good bit that is in your TC that doesn't get changed. When you flush the tranny it pumps new fluid all the way through your tranny. I do a tranny flush every other time and the drain and filter the next. I change mine every 15000 miles and if race a lot then I change it a little sooner but thats just me not evryone does that.
Better than guessing what's in there and when it was
changed last. But I would have the flush followed by a
filter change. These trannies need all the kindness they
can get.
changed last. But I would have the flush followed by a
filter change. These trannies need all the kindness they
can get.
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
I'm not an expert, but I know form experince that changing fluid on a very high-mile tranny can sink it ... at 68k I would typically do the flush, but your dark fluid is worrisome ... sometimes the only thing holding them together is the gunk. It's a roll of the dice, but if I were you, I'd probably do it.
Thread Starter
Teching In
Joined: Jul 2005
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Thx! Thanks for all the replies.
Looks like im gonna do the flush followed by a filter change then. If the tranny does die then.. thats what warranties are for.
Thanks for all the advice-- was curious what other f-body owners did w/ the tranny flushing/fluid.
Looks like im gonna do the flush followed by a filter change then. If the tranny does die then.. thats what warranties are for.
Thanks for all the advice-- was curious what other f-body owners did w/ the tranny flushing/fluid.
i race mine...never done a tranny flush. I change my fluid after every 4 times to the track and the filter after every 8. Main thing is to keep clean fluid in it and it should last 
Teching In
Joined: Jun 2005
Posts: 10
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From: Cumming, GA
If you are going to do the flush, drop the pan and change the filter
FIRST. This allows you to examine the trash in the pan and decide whether there are any upcoming problems. Flushing first will circulate the trash in the pan through the transmission. Remember, the pan holds the dirtiest fluid in the trans. Get it out of there first before flushing. I would NEVER flush a transmission without first dropping the pan and examining the debris.
transman
FIRST. This allows you to examine the trash in the pan and decide whether there are any upcoming problems. Flushing first will circulate the trash in the pan through the transmission. Remember, the pan holds the dirtiest fluid in the trans. Get it out of there first before flushing. I would NEVER flush a transmission without first dropping the pan and examining the debris.
transman
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Flush is only going to replace the inline fluid, pan debris
has to traverse the filter. If you replace the filter first
than anything the flush sweeps out, will be in the pan
until the next change.
Maybe you should change the filter before -and- after,
just to make us all happy
has to traverse the filter. If you replace the filter first
than anything the flush sweeps out, will be in the pan
until the next change.
Maybe you should change the filter before -and- after,
just to make us all happy
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transman618 has this one partly right. Examine the trash in the pan and decide whether there are any upcoming problems. If everything looks ok, very little metal on the magnet, no clutch/band material on the bottom of the pan away from the magnet. Then repalce the filter, clean the magnet, new Duraprene pan gasket (65-75 inch pounds torque on pan bolts, no sealer), add 5 quarts of "quality" fluid. Now drop the lower transmission line at the radiator and have a large container that you can see the fluid going into. Have a funnel in the dipstick tube with at least 5-6 quarts of fluid open & ready to pour. Start engine and add fluid as fast as possible, all the while monitoring the fluid leaving the bottom line, as soon as the fluid changes color (new fluid color) turn off the motor, reconnect transmission line, start motor and top off fluid. Now this is an apx. 98% fluid change, and for much less than the oil changing places that do this.
Staging Lane
Joined: Jan 2005
Posts: 56
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From: southtown
well, since i flushed my tranny i will post up my experience. no problems as of yet and the flush was 4 months ago. it is my daily driver and every once in a while i get on the throttle, but not much. have not noticed any changes in shifts, etc. all seems good to me at this point. the fluid was very dark when changed. btw this was on my 99 formula which had 70k miles on it.
