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2004 Corolla S: Transmission Flush


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#1 CARDIS

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Posted 22 May 2016 - 11:23 AM

Good morning.
 
I took my 2004 Toyota (around 117,000 miles) to the dealership the other day to fix the latest recall. They performed their required (free) multi-point inspection before installing the recall fix and reported my transmission fluid is dirty.
 
Now, I've had problems with this dealership in the past. They've tried to scare my mother into brake services by telling her they needed immediate replacement and when we took her car to two independent shops afterwards, she was told by both they were perfectly fine.
 
Because of that, I checked out the transmission claim and found it does need to be changed, but the mechanic who has done most of the work on my car highly recommends doing the transmission flush at the dealership because he's seen flushes go wrong much more than you'd think (due to changing pressure on other parts) when done by anyone other than the dealership. I reluctantly double checked the paperwork and found their estimated services include a "BG Trans Kit" and 12 quarts of transmission fluid. I wanted to research this myself but so far I've seen conflicting information about the usefulness of flushes, as well as varying accounts of the amount of fluid required (even the mechanic I mentioned earlier side eyed the 12 quarts estimate).
 
Has anyone experienced this themselves? Do you think I need a flush or could I get away with a drain and replace instead? I'm going on a road trip at the end of the month so I want my car in top shape, but I'd rather not get scammed by a greedy dealership in the process.

#2 fishexpo101

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Posted 23 May 2016 - 11:51 AM

If you have been doing routine ATF fluid replacements, other words, you've replaced the transaxle fluid before on this car - then a drain and refill should be all you need.   For this generation - under most conditions, drain and refill (~4 quarts of Toyota Type T-IV ATF) every 60K miles is just about right.

 

The factory service manual actually says it is only necessary to do only drains and refills - a flush will not buy you anything else, unless you need to do a complete fluid exchange due to wrong fluid introduced into the system, or if there are signs of excessive fluid oxidation (been towing with the car, abusing the transaxle). 

Note that you CAN'T really tell the condition from the "look or color" of the oil, it could be very dark in color, but still provide good service.  The odor on the other hand, is more telling.  If the oil smells "burnt" and the fluid is excessively dark in color, then you should get the fluid flushed out soon than later.  Might be worthwhile to open a bottle of fresh fluid, note the odor of the fluid and compare it to fluid in your transaxle.

 

That BG Trans Kit is just extra money for the dealership - they don't have to use it to properly do a flush.  Basically it is two cans of additives - one transaxle conditioner, one transaxle cleaner - both are NOT recommended by the manufacturer.  Dealers like it because they get to add more to the bill, plus some marketing money from BG Products Inc.  Possibly tied into the machine they use for the flushing process.  They also don't have to drop the pan or clean/replace the filter in the side the transaxle - basically, it is the dealership being lazy.  Biggest issue with this design, since they don't take the pan off - any junk that is on the bottom will be lifted by the solvent additives they just pumped in and circulated through the transaxle before they get sucked into the machine.

 

The "safest" method - is to do a couple of drains and refills over a short period of time.  Drain and refill - drive for a 500miles to 1000 miles, drain and refill again - drive a bit longer - do another drain and refill if the burnt odor is still present or if the fluid visibly darkened from the last change.  That gradual replacement of fluid will not harm the transaxle and the very first drain and refill will return a significant portion of additives in the fresh fluid to protect the transaxle. 

 

If you are feel comfortable turning a wrench yourself, you could also opt for a DIY flush - lots of information / videos online to do it.   Best part of this, no added additives, just clean fluid.  Short take on it:

- drain the fluid from the transaxle pan, then drop the pan

- clean the pan and pan magnets of metal shavings

- clean or replace the transaxle filter, replace the pan, drain bolt with new washer

- refill with fresh fluid

- disconnect return-side cooler line and attach a section of clear tube to it, run that into a bucket graduated with quart lines

- start car in part, fluid will start to flow out of the cooler line into the bucket at a steady rate 

- run car until fluid flow it just starts to slow/sputter - Shutoff engine, refill with the exact same amount that was drained into the bucket

- repeat process until fluid runs clear pink/red

 

Whole process will use about 12 quarts of fluid - every bit as effective as a professional flush, but without any additives and you've cleaned the pan.

 

You can ask the dealership to do an inlet pump flush, without the BG "kit" - but some shops don't have the equipment to do it, won't do it.  Inlet pump lush basically does everything the DIY does, except there is a special plate that attaches to the inlet pump on the transaxle.  They have to drop the pan and remove the filter to attach it - that's why I like it.  Oil fluid never circulates through the system, doesn't circulate any bottom of the pan junk through the transaxle - which is what kills transmissions when they flush them.