Should I change the Automatic Transmission fluid 120K

[Blaster2005]

I'm wondering if I should change the Auto transmission fluid on this Aspire. I was told that the new fluid has detergent that may cause it to start slipping. I'm big on doing service on a car, however if it can cause transmission falure is this a good move? The car has 120k probably never been changed but shifts good.

Second question if i do change it, should I use dextron 3 or mercon v? This is an automatic transmission.

All advice appreciated!

Thanks,

Mike

P.S. I posted this the other day in the repair forum with little result. I'm really hoping someone has good advice on this topic.

[FB71]

no, the detergent in trans fluid will NOT cause a good trans to slip. All trans fluid for the past 30+ years has detergent in it. I typically advise customers and techs to change fluid at 60k mile intervals, unless the manufacturer has other very specific instructions to change more often, or not at all.

Dexron/Mercon III is what you should use. Stay away from Mercon V for our applications.

Sorry I missed your post in the repair forum.

[Pu241]

FB71,

I have used Mercon IV as Mercon III isn't always available.
Why not Mercon V?

[collegeboi]

not to jack your topic but just wondering how much quarts (i think) i would need for my 89 carbed 4 speed.

[FB71]

FB71,

I have used Mercon IV as Mercon III isn't always available.
Why not Mercon V?

Mercon IV?

Who markets that, because Motorcraft doesn't that I have seen.

This might be an aftermarket industry label for gen2 Mercon III.

In fact, it looks like Motorcraft has recently realigned its products (again)

Transmission Fluids
MERCON® V Automatic Transmission Fluid
MERCON® SP Automatic Transmission Fluid (5R110 TorqueShift in the diesels)
Premium Automatic Transmission Fluid (this would be equal to Mercon III)
Continuously Variable Chain Type Transmission Fluid
FNR5 Automatic Transmission Fluid
Ford Type "F" ATF and Power Steering Fluid
Premium Power Steering Fluid
Full Synthetic Manual Transmission Fluid
SAE 75W-90 API GL-4 Gear Oil
SAE 75W-90 Premium Synthetic Transaxle Lubricant


Type F, Mercon, Mercon III are full dino oils. They each have a different coefficient of friction. Mercon V is a dino/synth blend. It has the lowest coefficient. Some of the chemicals in V will attack the adhesive used to bond the friction material to the plates and band, eventually resulting in trans failure.

[Pu241]

FB71
This was some years ago!
Might have records somewhere on Mercon IV purchase.
So can Mercon V be used in a manual tranny without issues?

[elcamino1]

So what can you use when no one carrys Mercon III or IV anymore.
John V should be fine in a manual trans!

[FB71]

Yes, Mercon V is fine for MTX, it only the ATX that presents an issue.

Any dino based ATF designated as a universal. If you read the label, it should indicate wether or not it is a suitable replacement for Mercon III.

[Hot_Wheels]

ok this isnt festiva related but i changed the trans fluid in my trailblazer and the trans hasnt felt the same since ive done it, i changed it at about 30k i think the dealer wanted me to do it at 20k and there also telling me to change my diff fluid but i heard it isnt needed, but ever since i let the dealer change the fluid it takes longer for the trans to warm up you can hear the trans is cold and doesnt want to move so i take it easy tile it warms up then some times it dont seem like its shifting right, last time i told them BEFORE i had the fluid changed they said they made some shift change points i wonder if i should have them go back to stock due to the new fluid?

[FB71]

dude, punctuation... It's hard to separate your thoughts otherwise...

yes, change your diff lube every 50-60k miles

If the wrong fluid was used, it can cause trans performance issue.

[(90festivalx)]

If your transmission is slipping what would happen if you changed the fluid? i heard that the type f tranny fluid can make a transmission shift slightly harder, well that was when it was used in a gm th350. Would that help fix my problem? The transmission feels like it is slipping as it changes gears in not sure if its slipping while it is in 3rd gear. I got the car and the owner before said all it needed was a brakeline so im not sure how the car shifted before I got it.

[marinepolice03]

how many miles on the car? im assuming you have a auto. changing the fluid on the trans if it was not serviced before could be very bad, beacuse the trans is depending on the dirty gritty fluid to help the trans shift and changing the fluid would only make it slip more.

[(90festivalx)]

The car has around 140,000 miles on it. Im not sure when and if it had ever been changed. i got the car this year and im not have any luck with it at all it sat for about a year untill i got it. But the fluid isnt really awful it shifts better when its cold and the fluid is thicker then as it warms up it slowly starts to shift funny. when i say cold i mean 30 degrees outside kinda cold.