How often should I change Auto Tranny Fluid? - Transmission Forum

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How often should I change Auto Tranny Fluid?
Sunday, August 07, 2005 10:42 PM
Pretty much what the topic says. Also, I have an auto trans interceptor if that matters. Just want to know when I should...it might say it in the manual but I haven't had a chance to look. If you can help, I'd appreciate it.



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Re: How often should I change Auto Tranny Fluid?
Sunday, August 07, 2005 11:51 PM
depends on how you drive it...... when I had my 97 Auto Z, I changed it every 10k miles, and the filter every 20......... but I worked at a dealer at the time, and it was all free......





SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Re: How often should I change Auto Tranny Fluid?
Sunday, August 07, 2005 11:59 PM
Well I'm at about $30,000 miles. How much does it cost to change the fluid (estimate)?
I might have to go to Jiffy Lube or something.



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Re: How often should I change Auto Tranny Fluid?
Monday, August 08, 2005 11:14 AM
never change it. might sound stupid but i would say more than half the people who change it end up having problems later on. I did.


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Re: How often should I change Auto Tranny Fluid?
Monday, August 08, 2005 12:17 PM
Well, chalk me up as one that didn't then... I used to change my tranny fluid & filter every year.. always synthetic stuff too. Never had a problem.... got expensive though. Still cheaper than replacing the tranny!!




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Re: How often should I change Auto Tranny Fluid?
Monday, August 08, 2005 12:36 PM
25 - 30 k if long interevals

10-20 like speedracerz said... if you can afford it... most should be able to...


just like all other fluids, excessive heat degrades it. let it go too long, start to burn and wear the seals bands and clutches from oxidation. as most know, heat is the biggest killer of auto transmissions.

operating range is 175-195...

every 20 over halfs the life of the fluid. most people who dont have external coolers or guages, usually easily get up in to 215 plus, especially if you drive in traffic. our radiators arent exactly massive...

heres a thing that should help...

http://ca.autos.yahoo.com/maintain/answer.php?automatic_transmission1.html

and also

Quote:

Automatic Transmission Fluid & Temperature
At normal operating temperature of around 170 degrees Fahrenheit , non-synthetic automatic transmission fluid will last about 100,000 miles before it begins to oxidize. As the temperature of the fluid rises, the rate of oxidation doubles and the life expectancy of the fluid is reduced by one half with each 20 degree increase in temperature.

In general:

Temperature Fluid Life Expectancy, in Miles
175° F 100,000
195° F 50,000
212° F 25,000
235° F 12,000
255° F 6,250
275° F 3,000
295° F 1,500
315° F 750
335° F 325
355° F 160
375 ° F 80
390° F 40
415° F Less than 1/2 hour

Obviously, then, transmission oil coolers are a good thing, especially when towing or severe use is encountered.



while alot of people might say a guage is needed, its def beneficial.





Re: How often should I change Auto Tranny Fluid?
Thursday, August 11, 2005 10:39 PM
If your not racing, and this is your daily driver, you should change it about 50k.

If I am not mistake the new J's have a "lifetime" fluid in them.

Fact is they are all pretty much lifetime for a daily driver, we keep alot of our cars into the mid 200,000s and never change our tranny fluid!
Re: How often should I change Auto Tranny Fluid?
Friday, August 12, 2005 8:28 AM
mine costed $60 in a 98 malibu with the 4t40e

i would never leave trans fluid in for a lifetime
Re: How often should I change Auto Tranny Fluid?
Friday, August 12, 2005 4:09 PM
Rob Smith wrote:If your not racing, and this is your daily driver, you should change it about 50k.

If I am not mistake the new J's have a "lifetime" fluid in them.

Fact is they are all pretty much lifetime for a daily driver, we keep alot of our cars into the mid 200,000s and never change our tranny fluid!



lifetime fluid is BS really...

almost any fluid breaks down with heat....

daily drivers normally clear 200 degrees and thats without external coolers.... and because of this depending on what temp yours regularly reaches, that should be a large determinant in when to change...

and even more so if you have any upgraded tranny parts, stall converter, auto trans, b-m shift improver, etc...

its like coolant...

150,000 mile coolant, but if your car is running hot, the properties degrade faster.



Re: How often should I change Auto Tranny Fluid?
Saturday, August 13, 2005 4:30 AM
If I can offer another tip,

when you drop the pan, make sure you clean the heck out of the gasket surface on the transmission. I mean it's got to be clean enough so you can practically eat off it. I've done pan drops a bunch of times and almost every singe time the damn things have leaked afterwards.

My advice would be to ditch the gasket that comes with the filter and get a RTV type sealant. There is this stuff in a can called "Right Stuff" You can find it at any autzone, pep boys, the usual. It comes in a can and it works really well. I did a pan drop on my Subaru to fix a leaky gasket and this stuff has not leaked yet. I highly recomend it.

Oh, Mobil1 synthetic ATF is good stuff too. Pricey though.




Re: How often should I change Auto Tranny Fluid?
Saturday, August 13, 2005 10:31 AM
well it may be tempting but dont torque the pan down

you'll just get leaks



oh and there are machines so that now they dont even have todrop the pan which if its only been 25k miles since your last filter change makes since

Re: How often should I change Auto Tranny Fluid?
Sunday, August 14, 2005 3:37 PM
should always check, replace, and possibly open the filter to see if there is any crap in there that could show signs to a imminent failure.

filters are def cheap to replace each time.


machines are great to flush it all out, but if at all possible def check the filters on anything you run.



Re: How often should I change Auto Tranny Fluid?
Sunday, August 14, 2005 5:46 PM
El Diablo wrote:well it may be tempting but dont torque the pan down

you'll just get leaks



oh and there are machines so that now they dont even have todrop the pan which if its only been 25k miles since your last filter change makes since


That too. The tourque spec on those bolts is tiny. I use a cordless drill on the lowest torque setting to put mine back in.




Re: How often should I change Auto Tranny Fluid?
Sunday, August 14, 2005 11:44 PM
Dang, only $60 for a flush?
I need to move.


-M


Remember....syringes go in the RED waste basket.
Re: How often should I change Auto Tranny Fluid?
Monday, August 15, 2005 4:15 AM
Mastin wrote:Dang, only $60 for a flush?
I need to move.


-M



not all flushes are equal though....

some require a cleaner to be added, then driven around for bit......

others a machine is hooked up to it....



torque is something like 4 ft .lbs...



Re: How often should I change Auto Tranny Fluid?
Monday, August 15, 2005 6:10 PM
Opening the filter is a good idea. I used to BEAT the crap out of my auto..... (neutral drops, manual shifting) One of the last times I changed the fluid I noticed a 1/2 coil from a spring stuck to the magnet......... didnt find anything in the filter, but the trans sure shifted hard into 2nd (would sqeak the tires every time it shifted above 5k rpm)





SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

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