transmission flushes, to flush or not to flush?

[Michael Garboski]

The lovely Automatic Transmission fluid, always a pain. The question is to flush or not to flush? I’ve heard people (including some mechanics) claim that transmission flushes will screw up your transmission and just generally cause trouble, yet there are still many shops that still offer this service.

What is everyone’s opinion on this? Is flushing neccessary? Will it ruin your transmission, or is it safer just to change the fluid?

or does it all depend on the situation?

Thanks in advance

Topic

[Erin]

The idea of flushing certainly looks good on paper.
Who knows if it really causes damage to the trans but it WILL cause unnecessary damage to your wallet.

Maintenance is something a lot of folks don’t think about til something breaks.
I heard it said that if a trans fails after a flush, it was probably doomed to failure to begin with.

Just a regular fluid change at intervals should be fine. If you do not know the service history, then especially do not flush it.
Who knows how long the previous owner let it just go.

[Bluesnut]

The thing about trans fluid flushes is that problems may be claimed to be due to:
“The high pressure from the flush machine can damage the internals….”. Most flush machines use the existing pump inside the transmission to circulate and flush the fluid so I have no idea where this excessive pressure claim comes from.

“The flush will circulate debris in the transmission and screw up things inside…”. The flush machine uses the existing pump in the transmission and the fluid is circulating from the pan, through the filter, and then on through the trans and cooling lines just as if the car was in normal use. The pump is sucking up fluid from the pan and through the filter just as it always does.

If someone has a “debris” problem then they’ve got a transmission problem; not a flush problem.

[Author]

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