How many drain and fills should I get?

Quick question, how many drain and fills would it take to get a higher percentage of new fluid than old fluid. So far I did 2 drain and fills a month apart and plan on doing another one before the end of the month. Never had a flush and it seem to lessen the hard shifts that I was starting to have. 263k miles. I go to an independent shop that specialized in Asian and import vehicles. He does use Toyota WS fluid. usually 3-4 quarts drain out and puts in same amount of new fluid. He lets it sit overnight and check temperature and level afterwards. After this, I’ll start doing it every 15k miles or at least once a year to keep fresh fluid.

 

2 or 3 to start is pretty solid. Then one every 15-30k miles is a good plan for longevity. You’ll never get it all clean without an exchange VS. a drain and fill. The drain and fill is however the easiest and least likely to create any problems.

 

Is a fluid exchange different from a flush?

 

a "flush" generally involves a machine that forces fluid through the system using pumps in the machine. A fluid exchange is usually done by using the transmission fluid lines going to the transmission cooler. The line coming out of the transmission is dumped into a waste bucket. The line going back has the fresh fluid being added back in. The transmission pump is still in charge of moving the fluid so external pumps aren't used to pressurize the transmission. Even this method involves some mixing of fluid in the transmission pan. Most will stick with the drain and fills.

 

I had mine "flushed" (which was not high pressure, just a full fluid exchange) I figured if it uncovered/created a problem, I'd rather know about it now then when I am on the road. 25K later, and I never had any issues.

 

Flush is not possible, there's no any port on the transmission that is not governed by some kind of a valve. Machine "flush" ends up in mixing ATF in sump and in torque converter, so it is not any different than drain&fill.

 

I'm a huge fan of drains/fills once a year.

The idea is to get fresh additives and lubricants in the mix constantly.

First drain and fill gets you 33% new fluid
Second gets you 55%
Third 69%
Fourth 79%
Fifth 86%
Sixth 91%

There are diminished returns in each change as an increasing portion of the fluid you are dumping is brand new.

Edit, these % assume 12.3 qts total and 4 qts per drain. Also that the fluid mixes homogeneously between drains/fills.

 

Add 2-3 oz of Lubegard HFM to your next d&f. It would replenish otherwise diminished friction modifiers. WS is not carrying much of them anyways.

 

This is good info I think I’m gonna try this myself this weekend. Due for a change anyways.

 

Are oil additives any good or are they a waste?

 

Depends on an additive. HFM is good. Friction modifiers is first what depletes in otherwise good ATF. Dull ATF causes more frictions wear. You don't normally need it if ATF is replaced routinely, but since you've been running your old ATF for so long... Just don't go over the roof with it.

 

Okay! So adding this would that help my rig with intermediate timing chain tensioner tick possibly …?? Maybe haha?

 

Sure thing, I soak my morning toasts in HFM, too!

 

Well I think I’m gonna start doing that too. Thanks for the tips

 

Would it be safe for me to get a fluid exchange although the trans service history is unknown outside of what I did? The 2 d&f I had done already has resulted in some improvement as it was shifting a bit hard prior.

 

Personally, I would give her another d+f or two. You can do quite a few more of them for the cost of a service.

 

FYI, I did 5 drain and fills when I first bought my 02' Sequoia with 156k miles......I don't think the tranny had ever been serviced. In between flushes, I would drive a few miles out in the country to get the new fluid mixed around and to open up the torque converter. I always just put the same amount back in that drained out. The 02' had a dipstick that you could check the fluid level with which is so nice compared to my 14' Sequoia now.
Here are the results. Definitely cleaned out most of the old fluid! Afterwards, I would do a drain and fill at each oil change or every other one just to keep it fresh. Sorry the first pic is blurry, but you can still see the difference. 1st drain on the far left, new fluid on the far right.

 

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