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No good aNswers iN the case of gMc’s slippiNg traNsMissioN

BY RAY MAGLIOZZI

Then, they said I have to drive another
couple thousand miles for the computer
to learn my driving habits again (what?).
The last time I took it in and told them I
was not happy, they said they contacted
the manufacturer or someone, and they
were told that they know about the
problem, and there is nothing they can
do. First of all, have you heard any such
thing, a transmission learning a person’s
driving habits? I have always loved my GM
cars and trucks, but what do I do about
this? This truck cost me over $55,000,
and I shouldn’t have this kind of trouble.
Thanks. — Mark

Dear Car Talk: I recently purchased a
new 2020 GMC Sierra 1500 pickup truck.
I have had GM products for over 50 years
and am finally having problems. My
street has a slight incline. When I leave
home in the morning and go uphill, my
I’m going to steal that line “go drive
transmission slips quite a bit from first to
it for a few thousand miles and then
second gear. This mostly happens when I
come back.” They were hoping you’d
first leave for the day. I don’t notice it later
be
abducted by aliens during that
on.
time, and they’d never see you again.
I took it to the dealer three times. The first Actually, modern transmissions do
adjust to individual driving habits. The
time, they said my truck computer needs
transmission computer uses a kind
to learn my driving habits and adjust
of crude artificial intelligence to learn
accordingly (what?). The next time, they
whether you’re a lead foot or a gentleman,
changed some module or something and
and the shifts get adjusted, subtly, to
said that should take care of it. It didn’t.

accommodate your driving style. But the
transmission doesn’t have to “learn” not
to slip.
Here’s what we know about this
transmission issue: When owners started
complaining about “slipping” or slow
shifts between first and second gear, GM
discovered that there was a problem with
a part called the “stator.” That’s not to be
confused with the tall guy who pulls you
over for doing 80 in a 65-mph zone. The
stator directs the flow of transmission
fluid inside the torque converter. And if
things aren’t directed properly, you can
have shifting problems. So GM made a
change to the stator so fluid wouldn’t
drain out of it overnight. But then, owners
started complaining about “harsh shifts”
between first and second gear when the
transmission was cold. In the past, GM
recommended a switch to a fully synthetic
Mobil 1 transmission fluid, which they
claim helps. But, after that, they gave up
and switched to the answer you got; the
mechanic’s shrug. Essentially, “they all do
that.”

So I’d ask them if they’d be willing to
try changing your transmission fluid,
being sure to use the recommended fluid
(Mobil 1 Synthetic LV ATF HP). But if
that doesn’t help, then you have a choice.
You can either have a slipping problem or
a harsh shifting problem. If it were me, I’d
take the slipping and leave it as is, because
harsh shifts drive me nuts — especially
between first and second, which you feel
every time you leave a traffic light. I don’t
think either problem will affect the life of
the transmission in a meaningful way, if
that helps you feel any better. Yeah, after
spending $55,000, I didn’t think it would.
Sorry, Mark.
***
Got a question about cars? Write to Ray in
care of King Features, 628 Virginia Drive,
Orlando, FL 32803, or email by visiting
the Car Talk website at www.cartalk.com.
© 2021 by Ray Magliozzi and Doug
Berman Distributed by King Features
Syndicate, Inc.

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