ATF life

SlowPoke · Mar 31, 2005

How long does fully synthetic and conventional ATF last? The price of fully synthetic ATF is exorbitant over here, but conventional (dino, mineral) ATF are cheaper, so will it be better if I run conventional ATF but change out the fluid at shorter intervals? Say, every 10,00km (6000 miles) I replace the ATF at the same time when I change out the engine oil?

TR3-2001SE · Mar 31, 2005

I think most of the experts on this site say it will last 30,000 miles at least. If you get a complete drain which you seldom get with an auto then 30,000 would be great. T-tech flushes are a complete change of fluid. I get about 50% with my Honda automatic drain so I change it about 15,000 which I think is about as good as necessary. Just use the standard stuff and get a resonable change interval and you will never have a problem caused by the fluid being contaminated.

JHZR2 · Mar 31, 2005

Below is an excellent post from the zr2.com site. Very useful.

http://forum.zr2.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=001669;p=1

JMH

quote:

There seems to be a lot of debate regarding when and how to service an automatic transmission, and what, exactly, a standard service consists of. Even though I'm not in the industry anymore, I was a certified diagnostician and tech in the automatic transmission repair industry and a service manager at a transmission shop. Here's my professional OPINION regarding automatic transmission service intervals and what's required.

Regarding service intervals… I’ve seen the most durable transmissions fail as early as 80,000 miles for no other reason than old, nasty fluid and a dirty filter. I’ve seen the most fragile of transmissions last 300,000 miles because they were serviced regularly! I recommend a normal pan/filter service (NO FLUSH) at 15k – 20k intervals for any vehicle that drives in mountainous terrain, tows a trailer, goes four-wheeling, or gets a lot of stop-n-go use. Vehicles that see mostly highway use in the mid-west can probably go as far as 30k/mi between services, but that’s the MAX!

It needs to be understood that ATF, whether synthetic or petroleum based, has several additives that make it perform is job correctly. There are FRICTION MODIFIERS that help the clutches grab (and release) when they're supposed to. There are VISCOSITY ADDITIVES that help maintain the "weight" of the "oil" for proper lubrication and hydraulic properties. There are DETERGENT ADDITIVES that help control deposits by suspending particles in the fluid until they can be filtered out. All of these additives need to be replenished from time to time, as they are "burned away" with normal use. The BASE oil in ATF doesn't really break-down the way engine oil does, so it doesn't really need to be replaced in its entirety, just refreshed. Five to Six quarts of ATF contain enough of these additives to ‘refresh’ the five to six quarts that remain in the torque converter and cooler lines when the pan is dropped. Therefore, it is not necessary to flush a transmission at normal service intervals.

A normal service STARTS with dropping the pan, which releases about 1/3 to 1/2 of the total volume of ATF. Only by dropping the pan can you replace the filter, so there's no way around this if you want to do a correct service! Once the pan is off, remove and CUT OPEN the filter! By examining the contents of the filter and the sediment on the bottom of the pan, an educated tech can accurately assess the condition of the transmission as a whole. It's ok to have SOME material in the pan and filter, but if you see any chunks (1/16" or bigger) of friction material or metal shavings, take the filter (contents intact) to an expert for evaluation, because you have problems. The little ½” circle of grey past in the middle of your pan is normal wear… Don’t panic, just clean it and continue with the service…

Modern automatics have a lock-up style torque converter that contains one pressure plate and one ring of clutch material. This clutch is very susceptible to overheating and slipping (anyone heard of the dreaded P1870 GM code?) and will start to crumble and shed material (that will end up in the filter and pan) if it starts to carbonize from heat. One preventative solution is to keep fresh friction modifiers (less slippage) and viscosity additives (better hydraulic pressure) in the fluid via regular maintenance.

Shops that suggest a flush and fill service instead of dropping the pan and changing the filter should be avoided. Shops that try to sell you a flush along with a pan/filter service at normal intervals are just trying to pay for their new flush machine a little sooner. A reputable shop typically charges about $70 to $80 for a service including bulk ATF, pan gasket, filter and labor. Chevy S-10 4x4’s usually warrant an extra ½ hour labor because the exhaust x-over pipe is in the way and needs to be moved, so be prepared to shell-out another $35 - $40 for that.

If anyone has any questions, please reply… I consider this PARTIAL payback for all the help I’ve received from members. If anyone wants to add to this or debate the contents, PLEASE reply! I love when someone can prove me wrong, because I’ll learn something new!

Kestas · Mar 31, 2005

A lot of it depends on the fluid temperature.

Temp...Life
175....100K
195.....50K
220.....25K (common operating temp for most vehicles)
240.....10K
260......5K
300......1K

[ March 31, 2005, 05:49 PM: Message edited by: Kestas ]

iceberg · Mar 31, 2005

Keep that fluid nice and cool and you will have a happy transmission. For $50 at summit you can get a B&M supercooler. That is the first thing all my automatic transmission cars get. Remember heat is the number one thing that kills a transmission. I wouldn't let ATF go more than 30,000 myself.

unDummy · Mar 31, 2005

Slowpoke, your plan to change the ATF at the same time as the oil and use a mineral ATF is great. Just make sure that it is the required fluid for your application, which you didn't mention.
I've seen certain troublesome transmissions blow before there 1st so-called 30k service.
Also, ATF UOAs haven't been too good. Change it more frequently!

I'm one of few who make the effort to change the ATF at every oil change. I service several vehicles and they recieve the same treatment. We don't experience the problems that other people have with their transmissions in similar vehicles.

SlowPoke · Mar 31, 2005

Thanks for all the great replies.

My tranny requires Dexron III ATF. Since I plan on changing the ATF at shorter intervals, can I get away with dropping the pan less often, say once after every 2 or 3 fluid changes?

Just out of curiosity, what happens if the Dexron III tranny gets filled with Mercon or Toyota Type F ATF instead? What sort of damage will occur?

Whimsey · Mar 31, 2005

SlowPoke,

Dexron III is the same as Mercon. However it is NOT the same as Mercon V. I don't know about the Toyota Type F ATF, sorry.

Whimsey

MolaKule · Apr 1, 2005

Toyota type "F" or Toyota type IV???

unDummy · Apr 1, 2005

quote:

Originally posted by SlowPoke:
Thanks for all the great replies.
My tranny requires Dexron III ATF. Since I plan on changing the ATF at shorter intervals, can I get away with dropping the pan less often, say once after every 2 or 3 fluid changes?
Just out of curiosity, what happens if the Dexron III tranny gets filled with Mercon or Toyota Type F ATF instead? What sort of damage will occur?

What vehicle??

Stick with a DexronIII or a backwards compatible fluid.
If dropping the pan is the only way to remove fluid, then buy a drainplug kit for it. Or, use a pela extractor(or make your own) to remove the fluid through the dipstick. A drainplug or pump would be easier than dropping the pan.

Elroy the Unique · Apr 1, 2005

It looks like a 30,000 mile change interval is the best.

Would the 30K change interval be the same regardless of dino vs synthetic fluid?

SlowPoke · Apr 1, 2005

sorry, it was Toyota Type IV.

I was looking for synthetic Dexron III but the oil stockist only had conventional Dexron III but he also carries synthetic Mercon V and the Toyota ATF. So out of curiosity, I want to find out what happens if the wrong type of ATF gets into a Dexron III only tranny

TC · Apr 2, 2005

"...but conventional ATF is cheaper, so will it be better if I run conventional ATF but change out the fluid at shorter intervals?"

Sure, syn is not needed for most folks if change-out is relatively frequent. But there's simply no need to go more frequent than 15,000 miles, and even that would be overkill for most folks. The comments below apply to conventional ATF.
***********************************************

"That's why most transmission experts still recommend changing the fluid and filter every two to three years or 24,000 to 36,000 miles or once a year or every 15,000 miles if a vehicle is used for towing or other severe service use."
http://www.babcox.com/editorial/cm/cm80140.htm

"Heavy stop-and-go traffic, frequent short trips, trailer towing; they all put your engine to the supreme test and can take a toll on your transmission. Under these tough conditions, you can help your transmission run better and longer when you follow the vehicle manufacturer's Severe Service schedule and change the automatic transmission fluid at the recommended intervals (typically every 15,000 to 30,000 miles)."
http://www.chevron.com/prodserv/nafl/auto/content/atf.shtm

"In automatic transmissions/transaxles, the recommended interval is about every 30,000 miles or 30 months."
http://www.valvoline.com/carcare/articleviewer.asp?section=hm&pg=ccr20010601tf

ATF life

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