Trans fluid change

[tc02]

I'm probably asking a RTFM question but I haven't stumbled onto the thread that sufficintly or difinitively answers my question, so here goes ...

I am the (new) nth owner of a 95 Q45 with 150Kmi that has dirty trans fluid (brown). The transmission seems to shift fine now so I'm not currently concerned about any impending failure.

I have found plenty of places that will do a transmission service (drop pan, change fluid, clean screen) and/or a machine flush.

However, I've run accross a few that warn that this transmission should be left alone with this many miles, in spite of dirty ATF. They cite instances of a transmission failing to work properly after a fluid change or flush.

Still others say that the ATF should be cleaned up asap.

Is there a consensus amongst the experts on how I should proceed with this vehicle ?

Thanks.

[juiceman]

Run from the man that says dirty is better. I think from my experince on this site the concensus will be to do a flush, pan drop and filter change asap. I think it would be wise to switch to a synthetic like Mobil one also

[landtodd]

I theory I agree, but I did have a Mercedes transmission fail the day after I changed fluid and filter once. Maybe too much crud broke loose.

[maxnix]

Clutch and facing material floating around in solution is never good for the transmision.

By the color alone, it has notified you the fluid has failed and will not meet specified performance. Change ASAP. Your transmission may fail tomorrow, but new fluid will not hurt it.

New filter too after the fluid exchange.

[tc02]

Ok, I took it to a transmission shop, they dropped the pan and found a lot of crud. They said that it would be better to just put it back on and drive the car till problems appear.

Unfortunately, I didn't get a chance to take a look at it. However, these guys have a good reputation around here and the fact that they didn't just change fluid and wait for it to fail so they could sell me repairs indicates good faith.

I don't like the idea of owning a time bomb now (although every car is to some extent). Is there any good that can be done for this transmission short of rebuilding it ?

[juiceman]

It is a gamble either way IMO

I would rather do the flusha nd deal with it because restriction in the transmission will cause many more thing to wear excessivly

I gues the question is does the repair shop want to not change because he knows it will be ok or because he will get a bigger repair in the future or he does not want to take the chance on you coming back and complaining that he did something to your transmission during the flush. Alot of ifs

[BIONICQ45]

I bought a 91 Maxima SE recently that had brown transmission fluid. I went and bought my mandatory mobil 1 and couldn't get a reputable shop to do the flush for me because of liability concerns. I got the same spill that you're getting so I took the Max to Superlube, signed a waiver and they performed the fluid exchange. That was about a month+ ago and no problems.

My sister-in-law has an 89 corolla (80k miles) with pitch black transmission fluid that no one will touch. I recommended that she get it changed but the mechanics said otherwise. She took their advice....I think the clock is ticking.

Keep in mind that the transmission flush is not a high pressure ordeal that whisks through the transmission breaking up dirt and clumps. It is simply a fluid exchange powered by the trans pump. Very low pressure as far as I know.

[tc02]

FYI, the explanation from those against fluid change in high mileage dirty transmission is this:

Burnt fluid has lost viscosity and detergents causing clutch sufaces to have more contact in turn generating heat and varnish. The varnish helps to maintain friction and clearances in clutch although over time it gums up the valves.New fluid with good viscosity and detergent action changes clutch behavior and may break loose varnish which has a chance of circulating and clogging a valve.Therein is the risk.

Anecdotal evidence (ex, BIONICQ45's experience) is that one might get away with changing fluid in one of these high risk cases. Maybe it depends on doing a proper flush (per http://www.nissaninfiniticlub....=5631)

I am thinking that if you can get the varnish removed without clogging a valve then maybe you're in the clear. Or, once clutch is varnished removing varnish will cause slippage ???

[PalmerWMD]

I think tc has a good angle on this:

I want to add, that I believe is it crucial to change the filter (+pan drop) AFTER the transmission flush.

That way crud knocked loose can be caught before it clogs stuff.

Fred..

PS:On a related note, I feel that a transmission cooler set-up w/ a bypass of the stock heatexchanger, will give less opportunity for crud to block those lines.

[BIONICQ45]

I know this thread is aged but I found this bad experience on maxima.org. Guys trans was ruined after a flush.

http://forums.maxima.org/showt...02913

[maxnix]

OR ws it already ruined before the flush? Difficult to tell by the information presented.

[Q45tech]

With brown/black ATF a single flush is never enough sometimes even after 2 flushes it still is not correct looking because of all the damage owners do.

To my knowledge we have never had a transmission fail after a flush [within 60 days] but sometimes we force owners to do more cleaning [pan drop filter change]........sorry sir it needs another one really dirty look at this paper towel [fluid spot vs new].

[Jberger]

Note on the "maxima" transmission post, according to the thread it was a manual, so I'd say there's not much correlation. . .