greekguy66

So for all those that have done it before me, is it better to flush the transmission fluid at a shop or simply drain and replace?<br /><br />i have a 2009 GX and it's time to do something for the Tranny. I normally do all the other fluid changes but wondering if it's worth actually doing a flush on it. <br />

chitown40

Let's get the word "flush" out of our vocabularies. Let's call it a complete fluid exchange or a partial fluid exchange. No one recommends "flushing" the transmission any more. The world flush is often synonymous with pressure, which we want to avoid on most if not all transmissions.

I personally am a fan of a complete fluid exchange. The Toyota/Lexus shop manuals only speak of a drain and fill, which would be considered a partial fluid exchange.

When I change my engine oil, I change all of it, not just 3 quarts. A transmission drain and fill will get out about 3 quarts, but the entire system holds somewhere closer to 14-15 quarts. When I did the complete transmission fluid exchange on my 2009 GX470, I used the transmission cooler lines to exchange all of the fluid. It is a PIA to drain 3 quarts, then refill, but at the price of the fluid, I found it was just worth it to change all of it and not mix old and new fluid. There are a bunch of write ups explaining exactly how to do it.

At 100k when I did mine, I saw no change in operation between old or new fluid. It was simply placebo effect and piece of mind.

BradTank

Regardless of what you decide, you're not supposed to really change the transmission fluid on these cars without TechStream type software. It's actually pretty involved, and the amount replaced has the be dead on perfect. I would only let a shop that's familiar with the procedure and had the right equipment like a dealership. I've heard horror stories where shops screwed it up and the transmission starts having problems.

It's not like the old days where you just drop a drain plug, empty 3 quarts and put in a fresh 3 quarts.

Here is a video of the procedure

greekguy66

Thanks for the feedback from both replies.

chitown40

Regardless of whether you drain and fill 3 quarts, or drain and fill the entire fluid capacity, you need to check the fluid level at a specified temperature. There is a procedure to put the trans in temp check mode by shorting pins on the OBD II connector and following a short procedure. I was unsuccessful at this working with my 2009 GX470. My old 2006 4Runner had no issue going into the temp check mode using the short method. With my GX470, I used Techstream to provide the transmission temperature - at that point I could accurately check the fluid level.

One piece of advice. Add about 1/2 to 3/4 quart extra from what you remove. Many of these trucks were underfilled from the factory or burned off a small amount of fluid during its service interval. You will end up wasting a good portion of it during the level check, but at least you won't be underfilled and have to go back and add more fluid and do the whole process again. If you're good, you can recapture the fluid from the level check and save it.

2008

I bought 12 quarts when I did my transmission fluid change at 90k miles (shortly after purchase). This was based on the stated capacity, but I think there was still a little bit of old fluid left. Probably 14 quarts if you want to get every last bit of old fluid out.

I did the cooler return line method .. very easy. To get level correct I used the OBD pin jumper method, worked fine, just need a paper clip. I now have a techstream computer, I'd have used it if I had it back then, slightly less work.

I will play devil's advocate here: because the fluid type (toyota ATF WS) and fluid level is very important, I would never let a shop do it. Much more likely that the shop will be lazy or negligent than that a DIY person following the correct procedure will get it wrong. Might take a little longer but you save big $$ and know it's done right.

Matsui

I'm at 145k with original fluid. I'm considering either BGE Transmission "flush" from my Toyota dealer for $250 which replaces all of the fluid with new WS fluid. Or buying WS fluid, pan and filter, and taking it to my indy shop to do a drain/fill several times. The first option seems less hassle but higher risk. Has anyone done the flush through BGE system and gotten good results? I have read all the threads here about drain vs. refill but there is no consensus which is better - most seem to lean towards drain/fill method.

ALAN553

my first GX was an 04, did just a fluid pan drain and refill at 60K and than did the entire fluid flush i think it was a Bosch machine at 160K, both done by lexus...no problems.

NTH

Well said.