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10 minutes to shift into 5th?

Howdy I drive a 96 geo prizm with an automatic transmission. The car is a great commuter and a real work horse except for the fact that its been having a hard time going into 5th gear. Lately on the highway I’ll be going 70mph for 5 minutes on very high res until it finally shifts into 5th gear. Yesterday it took 10 minutes driving at 70 for it to shift into 5th!

Is this something I should really be worried about (as in transmission replacement?) or is it a smaller fix?


The computer is programmed not to engage the torque converter clutch until the coolant reaches a certain temperature. This allows the engine to heat up faster thereby reducing emissions.

One thing that can cause it to take longer for the torque converter clutch to engage is a partially stuck open thermostat.



Hat’s off to tester. I too was going to commend on the recent deep-freeze weather on the operation of transmissions. Where do you call home?

I live in oakland california, it gets cold but not too cold.

awesome super helpful thank you. glad my tranny isn’t dying.

Yes, it probably isn’t dying, but it would still behoove you to check the level, color, and odor of the trans fluid.
And, if it has been more than 3 years since the trans fluid was changed, you really need to attend to that vital maintenance.

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Concur w/ @VDCdriver above , if there’s quite a few miles on the transmission since the last proper service, now would be a good time. A proper transmission service usually involves dropping and cleaning the pan, sieving the fluid drained for signs of metal debris, replacing the filter, and refilling. Shops often do this w/the help of a flush machine. That’s ok. But if a shop simply wants to hook your tranny up to a flush machine without dropping the pan, etc, best find a different shop who’ll do the job correctly

I would change the thermostat if it’s over 10 years old, even without symptoms.
They’re not expensive.
Use only OEM (i.e. from Toyota), many aftermarket units are junk.
Change the radiator cap too.

According to the National Oceanographic and Atmospheric Administration (NOAA), the temperature in Oakland isn’t currently much higher than it is in NH, but I don’t know how to access historical data. What’s it been there these past weeks?

By all mean get it checked out by a reputable tranny shop, but if it’s been dropping below freezing at night and still cold in the daytimes recently, that may be the reason.

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The 1996 Geo Prizm did not have a 5 speed automatic transmission available. 1.8L models could be had with a 4 speed automatic, and 1.6L models could have a 3 speed automatic. It’s never going to shift into 5th gear no matter how long you wait.


+1 to @FoDaddy I’d guess what you think is 5th gear is the torque convertor locking up and yes 10 minutes is too long.

thanks, my dad was worried that it wasn’t going into overdrive.

haha oops my bad thanks for the clarification!