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Transmission shifts hard until fluid is warm

EDIT: car is a 2000 Nissan Altima

When I first got my car it would shift hard from 1-2 and 2-3. My father changed fluid with aftermarket and problem went away but I don’t know what fluid he used. A few months later the torque converter was acting up because the thermostat was stuck open but I didn’t know why at the time. So I took the car to a transmission guy. He replaced the torque converter and said he rebuilt the transmission, replaced the solenoid pack and changed the fluid. I don’t know what kind of fluid. Since I got the car back it is shifting really hard from 1-2 and 2-3 again until I drive it for about 15 minutes. After 15 minutes it shifts smoother but not as smooth as it did before I took it to him. I’m thinking of changing the fluid. So if this time the problem is the fluid, would I need a thicker or thinner fluid than what he put in it?


If anyone is wondering, when the thermostat stuck open it wasn’t allowing the engine to reach full operating temperature which restricted the torque converter clutch operation. It happens with some cars. So in this case, all I had to do was replace the thermostat rather than messing with the transmission and torque converter

What car? I don’t see ANYthing that tells me what make, model, year, this car is.

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With out at least some identifying info, I see more questions than answers in your future.

Lets see if I have this correct.

  1. Transmission shifts hard

  2. Dad changes fluid and ruins transmission with wrong fluid but it shifts smooth.

  3. Transmission rebuilt and shifts hard with proper fluid

  4. Replace thermostat so engine gets up to proper temp and torque converter locks up properly

  5. Wants to put in wrong transmission fluid in so transmission shifts smooth

Shifted fine before paid for overhaul. Warranty?


Car is a 2000 Nissan Altima

Shifted fine after changing fluid with aftermarket of uknown type

Transmission acted up later due to the thermostat and ECU, it had nothing to do with the fluid, that fluid did not damage the trans or make it act up

After rebuilding the tran due to misdiagnosis, the transmission guy put NEW fluid in it.

The car shifted hard again as soon as I got it back. The shifts get smoother after driving the car for 15+ minutes. Im not sure if fit is because of the new fluid the trans guy put in it or something else such as the solenoids that he claimed he replaced.

My question is would I need a thinner or thicker fluid IF the new fluid is the problem? I don’t even want to bother asking him what kind of fluid he used because it turns out he’s cheap and a liar

you paid for a properly functioning trans. what does the trans guy say when you tell him it shifts hard? uh, he didnt “fix” that part of trans during overhaul? so he is not responsible for all parts of the trans?
why are you focusing on fluid?

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He doesn’t care that it shifts hard, claims that it’s fine. He did it privately for half price. It wasn’t shifting hard before I took it to him. Something he did made it shift hard again. I’m focusing on fluid because fluid had fixed the same problem in the past.

Have you verified the fluid level?

fluid level is fine, thanks

EDIT: Alright well it turns out the transmission guy used Dex VI which answers my question because Dex VI isn’t recommended for these cars and I read that someone else had similar problems after a dealer put the same stuff in theirs

well, since you paid for the transmission work privately and have no warranty, and since you know fluid is of wrong type, you have to stop driving it immediately and replace fluid 2-3 times now to flush the bad fluid out before putting more miles on the car

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Is this because not all of the fluid comes out when you drain it from the plug/pan? Thats what I heard

its a new/rebuilt trans. you can safely have a flush machine do a full fluid exchange now. there are no bits of crud inside that will be disturbed or loosened.


I used to have 2000 Altima and that generation is prone to hard upshifts on 1-2

I do confirm that changing fluid makes it better

transmission has a drain-plug, easy to get fluid replaced, it drains something like 60-65% of the rated capacity this way, so you have to drain/fill, drive for 10-15 miles to get fluid cycled in torque converter and radiator, then repeat

I had a good experience with Valvoline Import Multi-Vehicle ATF, it was rated to meet manufacturer spec and it is synthetic at quite reasonable price.

The spec (from my recollection) is Mercon II/III

they have some kind of additives which make shifts less rough, but I’m not sure if this is that or the fact the fresh fluid was added to the unit, go figure :slight_smile:

Thank you dragon.Yes, I was actually going to use valvoline mercon v which is also dexIII compatible. Someone else said they used mercon v in their 2000 maxima (which has the same trans) and it was shifting beautifully. They said it is better than dexIII and just below fully synthetic which makes it perfect for higher mileage trans’ since I’m not even sure the guy actually rebuilt it

EDIT: meant to say Matic D, not Dex III

Why is everybody mentioning Dexron and Mercon . . . ?

According to my source, a 2000 Altima is supposed to get Matic-D

I just looked up Valvoline Import Multi-Vehicle ATF . . . it’s definitely recommended for vehicles requiring Matic-D

So is Valvoline’s Mercon V

Plus I forgot to mention that he put a Ford torque converter in it, lol. This Valvoline Mercon V is recommended for both Nissan matic D and Ford

Dex VI is OK to use in this transmission. It’s a synthetic so it is thinner at cold temperatures and that is why it shifts better.

It does not shift better when it’s cold. It only shifts half decent after the car’s been running for a while. I’ll verify this if the fluid exchange fixes the problem