Should I change my transmission oil - Toyota Nation Forum : Toyota Car and Truck Forums

jasguild · 01-12-2011, 09:57 AM

I have a 1997 Camry LE with 240,000 miles on it (I plan to get at least another 50,000 miles on it befoer I retire her). In either case, I was planning on changing my transmission oil until I recently read online where a supposed mechanic suggested otherwise. His logic was that with the number of miles, if it is running, its not worth messing with it.

Does this make any sense?

I have not changed transmission oil on this car for the past 100,000 miles.

thanks

***Mister_Perkins*** · 01-12-2011, 11:00 AM

some people say that it will hurt the transmission, some people say it will not.

I've changed transmission fluid that is very old (100,000 or more) and the customers didn't have any problems. my .02

jasguild · 01-12-2011, 11:06 AM

I guess, the other question is what is the risk of drivinng it with oil that has not been changed for over 100k?

Is it like engine oil where the loss of viscocity means the engine parts will start suffering from accelerated wear?

***Mister_Perkins*** · 01-12-2011, 11:08 AM

yeah the transmission oil will break down just the same as motor oil. Eventually it will loose its viscosity and start to accelerate wear. That's why people say that its not good to change the fluid because they think the new fluid makes the transmission slip or something.

jasguild · 01-12-2011, 11:17 AM

hmmm. Is there any science to that or just an Old Wife's Tale?

***Mister_Perkins*** · 01-12-2011, 11:20 AM

I've never seen any data confirming that changing the oil will make it slip, but thats just what everyone thinks. Like I said I've changed ATF in customers cars with extremely extended ATF Intervals and they didn't experience any problems at all.

I will look around the net for some data confirming it, but apparently everyone thinks the old fluid helps keep the clutches to grab nicely and if you change the fluid it "washes" the fluid off the clutches and makes them slip.

EDIT:
http://www.trustmymechanic.com/transslip.html

apparently if you are experiencing slipping or harsh shifting its better to leave the fluid in there, but if your not experiencing any symptoms of clutch slippage then its alright to change your fluid

uibalnme · 01-12-2011, 11:46 AM

Change it, Change it, Change it, Change it!!!

These car will outlast the universe if properly maintained.

jasguild · 01-12-2011, 11:47 AM

Mister Perkins

thanks for your insights!

jasguild · 01-12-2011, 11:56 AM

Quote:

Originally Posted by uibalnme

Change it, Change it, Change it, Change it!!!

These car will outlast the universe if properly maintained.

My problem is, I have not properly maintained it. I am only now trying to do that at 240,000 miles

71Corolla · 01-12-2011, 12:05 PM

Quote:

Originally Posted by jasguild

My problem is, I have not properly maintained it. I am only now trying to do that at 240,000 miles

This is your best advice:

Quote:

Originally Posted by Mister_Perkins

apparently if you are experiencing slipping or harsh shifting its better to leave the fluid in there, but if your not experiencing any symptoms of clutch slippage then its alright to change your fluid

uibalnme · 01-12-2011, 02:00 PM

I remember when I got my 1st gen3.5. The shifts were a bit slow, and harsh. The ATF came out black as coffee, and probably with the same wear protection as coffee. I sure some damage was done, but after an ATF change the trans shifted as smooth as silk, almost undetectable until that car came to an unfortunate end a few years ago.

I would never do this, but if believe the myth of never changing old ATF because it'll do more harm than good...

You could drain the ATF, pull the pan off, pull the ATF strainer off, and check for any heavy wear deposits. If there are heavy deposits on the magnets, and in the strainer, without touching the deposits, reinstall the strainer, install new pan gasket, reinstall the pan, and pour the old fluid back in.

That's probably THE dumbest thing I've ever thought of. Seriously, we're talking about automatic transmissions that are light years beyond anything that would have been found in cars from the 40's, and 50's when changing super old ATF would have really caused damage. That's likely that's era when that idea started anyway. In modern transmissions, the clutch materials are much improved, and more durable than what would have been available 30 or 40 years ago.

Changing the ATF can only help these transmissions. Even if the proper maintenance was lacking before, if you start now the car will only get better.

That's my view on the subject...

reluctantmechanic · 01-12-2011, 02:44 PM

Not sure I can add to the above

But as mentioned

1) Changing it might knock something loose, causing a failure

or

2) Change it, cause changing fluids is good.

Personally, I suspect that this myth (#1) was born by because folks with transmissions that were failing and figured they would change the trans fluid as a fix....and it didn't work, the trans fails, and the next thing you know, they're blaming the fluid change on the failure.

I'm a compulsive fluid changer, and even if it might cause harm, I would change it anyway....

Do let us know what happens either way....I wish "Mythbusters" would test this one.

***fenixus*** · 01-12-2011, 03:15 PM

Quote:

Originally Posted by jasguild

hmmm. Is there any science to that or just an Old Wife's Tale?

it's an old myth probably from many years ago. I'm sure the oils structure got improved way beyond imagination from back then, so changing it for a fresh one is ALWAYS a good idea.

... unless your tranny box is screwed up already to the point where you want to do a flush just because you realized it shifts/slips tragically and is junk already hehe. then the last thing you do for it is a flush and what can you blame after tranny dies? of course the fluid flush and not the lack of maintenance on it for the whole life of a car

uibalnme · 01-12-2011, 03:23 PM

A complete flush isn't a good idea at this point, because it definitely can dislodge a big chunk of whatever's in there and cause a problem. A complete flush removes all the old ATF in the pan, converter, and gears. A drain, and refill, on the other hand, really only changes what's in the pan. It only changes ~2.5qts of the total capacity...which escapes me right now, but it's greater than then 2.5qts.

A simple drain and refill will slowly remove any deposits, and help protect the trans from any further damage. When I got this Camry, I did a drain, and refill on the trans, and diff. every other month for the 1st year I owned it to clean the trans/diff., and get all the old fluid out. After that I followed up by changing the strainer, and pan gasket. Now I drain, and refill the trans, and the diff. every 15k miles or every 3rd oil change. Just as my last gen3.5 the trans still shifts nice smooth.

OceanView · 01-12-2011, 04:37 PM

I'm in a similar situation and I will be changing my Transmission and Differential Oil this weekend.
My main question is which type of fluid should I use for both?
The Haynes Manual recommends Dextron III but when I called Toyota they said Type 4. Also what are your thoughts on Synthetics?

Hopefully this will help out the OP as well.