# transmission fluid change?



## Amber (May 5, 2005)

I have a 1990 Nissan maxima and i'm not sure if the transmission fluid has ever been replaced. I was told i should get it changed by one mechanic, i should flush it, by another mechanic, and i shouldn't do anything because it will mess it up, by another one. I don't know if i should change it or leave it. Can someone tell me?


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## GRNMAXDMON (Jan 18, 2005)

Amber said:


> I have a 1990 Nissan maxima and i'm not sure if the transmission fluid has ever been replaced. I was told i should get it changed by one mechanic, i should flush it, by another mechanic, and i shouldn't do anything because it will mess it up, by another one. I don't know if i should change it or leave it. Can someone tell me?



how have u had the car for??? if i were u i should change the fluid. take it to a reputable shop though. don't have backyard mechanic do it for u. i use to do mine every so often until i came across a 5 speed tranny and did the conversion myself. but i would change the fluid if it was me.


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## Matt93SE (Sep 17, 2003)

The problem with it is that if the fluid is actually THAT old, you can actually do more damage to the tranny by changing it...

the clutch bands and other parts have worn over time and developed sediments in the tranny.. so the inside of the case is coated with fine particles of nasty stuff.

New tranny fluid has TONS of detergents and stuff in it to keep these sediments from sticking to anything- so the big problem with changing your fluid now is that the new fluid can cause the sediments to break loose from the tranny case and start floating around in your fluid again.
This causes more wear on the clutch bands and other internals of the transmission and has also been known to get particles stuck in the valve body of the transmission- the part that controls the shifting....

So you can see why one guy said not to change it at all. I've seen many a transmission failure within weeks of flushing the fluid on a car that's never been changed like this.


*IF* you're going to change it, the best way to do it is to do a complete flush, drive on it for a day or so, then remove the valve body and clean/rebuild it and flush the trans fluid again. that will be pretty expensive though- looking at several hundred in labor. and another couple hundred for two flushes.


So my advice would be to simply change the fluid- pull the drain plug and let it drain out just like you would when changing your oil. then put the plug back in and refill to the proper level.
this will only change about 1/3 of the fluid in the transmission, so that small smount of new fluid shouldn't shock the system and cause the thing to self-destruct like flushing it.


Unfortunately you're stuck between a rock and a hard place. do one thing, it could fail.. do something else, it could fail... leave it alone, and it can still fail. eek!


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## GRNMAXDMON (Jan 18, 2005)

Matt93SE said:


> The problem with it is that if the fluid is actually THAT old, you can actually do more damage to the tranny by changing it...
> 
> the clutch bands and other parts have worn over time and developed sediments in the tranny.. so the inside of the case is coated with fine particles of nasty stuff.
> 
> ...



i'll stick to Matt's answer cuz now to think of it i had a similar problem with one of my auto tranny's back then with the same symptoms that Matt said so he's right on this. so its kind of hard to decide on what to do in ur situation.


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## Bror Jace (Apr 26, 2003)

While I agree changing the ATF _could_ stir up trouble (But I would _still_ drain off as much as I could and top off with new fluid) the following statement is a widely held myth which is incorrect:

_"New tranny fluid has TONS of detergents and stuff in it to keep these sediments from sticking to anything ... "_

ATFs have very few detergents, actually.

Doing some reading at BITOG and you'll find more info on this.


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## GRNMAXDMON (Jan 18, 2005)

this is gonna be good.


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## brianw (Feb 25, 2004)

I would just leave it. You've got sediment probably stuck to the drain plug and filter screen in the transmission. Stir it up and who knows how much of it you'll be able to get out without a proper cleaning and rebuild...


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## kbohip (Dec 14, 2005)

After searching around for a while this was the closest thread I could come up with to my question. I looked in the owner's manual on the '91 Maxima I bought a few weeks ago and it says to just inspect the auto tranny fluid at certain intervals. It never says to bother changing it. :wtf: I checked the fluid and it seems clean and red as can be. I'm guessing the previous owner had it changed as the car has 64k miles on it. Do you guys change the fluid in your auto's around here or just go by what the manual says and inspect it?


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## internetautomart (Mar 8, 2004)

I just make sure it's full


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## alexnds (Oct 1, 2005)

*transmission fluid*



Amber said:


> I have a 1990 Nissan maxima and i'm not sure if the transmission fluid has ever been replaced.  I was told i should get it changed by one mechanic, i should flush it, by another mechanic, and i shouldn't do anything because it will mess it up, by another one. I don't know if i should change it or leave it. Can someone tell me?


The 3rd Gen Maxima has no filter in the transmission so I'm sure it's pretty dirty. But it doesn't mean its viscosity is broken down, it's just dirty. So it is still lubricating things. Changing it should not in theory hurt anything, but the tranny tolerances might be "sloppy" now and used to the thick stuff that is in there right now. By comparison, fresh fluid will seem "thinner" by comparison, even if it's same grade of fluid. So flushing it with the machine will replace better than 90% of the fluid, but doing it by just dropping the pan and topping it off with fresh fluid will probably give you something like 60% old fluid and 40% fresh fluid, which in the end, is probably a better situation. If your car only has 60k miles on it, I wouldn't worry about it too much, and if the fluid is still pink and so forth and everything shifts fine, I'd leave it alone.

My suggestion is to put a magnet on the transmission pan, and let it sit there for a week or two. This will attract any fine particles if there are any. 

If you are worried about extending the life of your transmission and that is your ultimate goal, a thing that is smart addition to an auto transmission car is to add a transmission cooler in series with the main transmission lines coming off the main radiator. You extend the life of the tranny by letting things run cooler. (don't get one too big however, as it needs to be warm enough to shift). Usually, U-Haul is a good place for a tranny cooler that will sit in front of your main radiator.

The transmission cooler also gives you slighly extra fluid capacity, about 1 quart, so that helps things too.


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## internetautomart (Mar 8, 2004)

there is a filter, actually a screen, but replacing requires removing the trans from the car.


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## alexnds (Oct 1, 2005)

*transmission filter?*



internetautomart said:


> there is a filter, actually a screen, but replacing requires removing the trans from the car.


Hmm, I didn't know there was a filter. the shop that changed my fluid said that 3rd Gens don't have a tranny filter like 4th Gen do. However, my advice is to add a tranny cooler to extend the flie of the tranny and get some extra capacity in there as well. Do you agree?


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## internetautomart (Mar 8, 2004)

alexnds said:


> Hmm, I didn't know there was a filter. the shop that changed my fluid said that 3rd Gens don't have a tranny filter like 4th Gen do. However, my advice is to add a tranny cooler to extend the flie of the tranny and get some extra capacity in there as well. Do you agree?


to clarify the VG A/T has a filter but requires the transmission to be removed from the car and the transmission case split in half to change it

The VE A/T (and later A/Ts) have a replaceable screen filter in the "normal" location


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## smj999smj (Jan 1, 2006)

I recommend simply doing a drain and refill using genuine Nissan type "D" ATF available at any Nissan or Infinity dealer. Type "D" is the original Dexron formula (as it was prior to Dexron II, II and IV) and is better in preventing sticking valves in the valve body than the new formulas of Dexron. It's about a little pricey at about $6/qt., but it is what's recommended by Nissan. I service my trans every 30000 miles.


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## 90maxima (Oct 20, 2005)

yea this is on topic with new transmission fluid/filter... i noticed since i have a nice performance muffler and cold air intake, when i run my car on comfort sometimes it shifts and it just sits up at like 5/6 rpms and just sits there it doesnt shift back down, but when i put it on power it shifts fine, also the handling feels better on it as well... but i'm not sure if that makes gas mileage worse or what not? should i be putting a certain type of fuel into my car or just 87?


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## smj999smj (Jan 1, 2006)

87 octane should do just fine; you may see a slight increase in performance and gas mileage if you use premium grade, but you'll have to be the judge as to whether it's worth the extra expense. Driving habits, driving environment and proper tire maintainance will have a lot more affect on gas mileage than whether you use the "power" or "comfort" modes. Either setting should not have an affect on "handling," which is will only change with steering and suspension mods or changes.


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