Bobk528

I own a 2000 RX300 with 62,000 miles and want to change the transmission fluid to synthetic by myself. The Lexus dealer has changed the transmission fluid during the 30K and 45K service. I understand that synthetic transmission fluid might improve my mpg by a mile or two, provide smoother shifting (not that it isn't already), and might help extend transmission longevity.

What is the proper method to drain out the conventional Lexus or Toyota transmission fluid and fill with synthetic? I was planning to use the drain plug and fill same amount with synthetic but that method would drain less than half. Would that mixture of old tranny fluid and new synthetic fluid be harmful or simply a waste of $$?

salimshah

As you pointed out the drain and fill will remove only a fraction of the fluid. Torque convertor and other locations keep a good portion of the fluid trapped.

The other two methods are powerflush (not reccomended) and the mix over time. Mix over time requires you to drain and fill over a short period of time repeatedly till the % of old fluid is reduced significantly. How many times ... I dont know.

The other question is, is it good to mix synthetic and non-synthetic? There are myths floating around but no one has pointed me to real data. For engine oil, companies sell sythetic blends ... so it might be ok to mix them.

Sorry for such vague answers. May be some one who knows can weigh on this.

Salim

Lexusfreak

Amsoil is compatible with Toyota Type IV tranny fluid & I have switched to that for my ES. Not a problem whatsoever.

Lexmex

I am a big RX300 guinea pig if you take a look at the list of mods below, but it only came after a lot of $$$, reading and experimentation...and there will be more coming.

I would like to see for those of you using Amsoil ATF what happens after using it for 15K miles and you need to do a flush and or drain and fill. What color is the fluid...any particles in the fluid, etc.

I have no doubt that something in this world can be a subsitute for Type-IV, but I would want to see longer term examination.

Incidentally, we have no Amsoil dealers in Mexico City (despite my asking Amsoil), so I find this kind of strange.

TunedRX300

We need to find a way to get more Toyota T IV out of tranny cooler and torque convertor. Look at # of times drain and fill needed to reach a 99% Amsoil when one drained out only 4.2 quarts from transfer case and tranny out of AWD 's capacity of 16 quarts.

Drain&Fill # Amsoil Capacity % Replaced
1 4.20 16 26.25%
2 7.30 16 45.61%
3 9.58 16 59.89%
4 11.27 16 70.42%
5 12.51 16 78.18%
6 13.43 16 83.91%
7 14.10 16 88.13%
8 14.60 16 91.25%
9 14.97 16 93.55%
10 15.24 16 95.24%
11 15.69 16 98.09%
12 15.77 16 98.59%
13 15.83 16 98.96%
14 15.88 16 99.23%
15 15.91 16 99.44%
16 15.93 16 99.58%
17 15.95 16 99.69%
18 15.96 16 99.77%
19 15.97 16 99.83%
20 15.98 16 99.88%

salimshah

Some where around the 11th fill, you get to the point of diminishing return.

It seems co-existance of the two fuilds does not cuase any problems. Can any one
with Fluid-Mechanics back ground make a defintive statement?

Salim

Lexmex

Tuned,

While on vacation, one dealer I used once, Lexus of Naples, did a complete flush job. Not sure if they are still doing that.

However, my dealer up in San Antonio used a method that used two different types of fluids that got a lot more than 26.25% out on the first shot.. I cannot remember what kind of system this was...but it was not just a regular drain and fill. They hooked up some tubes and some fluid went in and then they drained the fluid. Don't ask me much more as I cannot remember the process too well now. I thought he told me that over 70% was removed on the first shot, but for the torque converter...but don't quote me on that.

I took it back one day later and we repeated the process. Vehicle felt much better afterwards...and very similar to when I had the flush done out in Naples. Fluid looked cherry red with a good smell.

This was a few years ago since I had this done...as I have drain and fill down here with Toyota.

I hope the Amsoil ATF works well for all of you...I do plan to switch from Mobil 1 to Amsoil for my oil once I get back to the states.

TunedRX300

Lexmex
Thanks for the tip, I also heard about it. Might be just open up the lines to the tranny cooler, line to tranny with Amsoil, and drain out Toyota T IV with the return line, start the car and stop when the color started to change. 70% on first shot will save us 3 drain and fill and about 12.6 quarts of expensive Amsoil.
Sounds a pretty non-invasive approach but anyone tried it?

Lexmex

That was somehow what I remember about that procedure that I saw, but this was a few years ago.

TunedRX300

I found the following from Amsoil FAQ web page. Actually I am not that far off.

"You now have replaced the fluid in the pan. To replace the fluid in the torque converter and oil cooler also, follow these steps.
Step 1. Obtain the total system capacity of the vehicle from the manufacturer or AMSOIL. Have this amount readily available.

Step 2. Disconnect the oil cooler line from the oil cooler. As you may not know which is the pressure side and which is the return side, have both directed so the stream of fluid will be directed toward a receptacle.

Step 3. With another person, be prepared to add ATF to the fill area as it is being pumped out of the oil cooler line.

Step 4. Start the engine, and as the old fluid is pumped out, add fresh fluid to the pan.

Step 5. When either the fluid color brightens or the total capacity has been replaced, shut the engine off and re-attach the oil cooler line. All fluids has now been changed."

Lexmex

Tuned,

Yep, that was what I saw except that they add some kind of different color (purple fluid) and when you no longer saw that fluid (and all cherry red)...they stopped. However, I remember he said for some reason some fluid still stays in the torque converter...not sure what the reason was, but I read this elsewhere, too.

TunedRX300

Lexmex, Thanks for the confirmation. We might have to shift gears constantly and applying both parking and regular brakes to get more fluid out of TC. My powertrain warranty will expire in 4 months and I will switch to Amsoil then. I have a feeling that you will get to it before I do.

Lexmex

Tuned,

My warranty was gone some time ago. The day it ended was the day that my modifications started, including the fluids.

Here is what I am using now:

PSF- Valvoline Powersyn
Brake- Valvoline Powersyn
ATF- Toyota Type-IV
Coolant- Toyota Coolant + Redline WaterWetter
Oil- K&N filter, with Mobil 1 5W-50 + 0W40 blend.

I also use Techron in the gas that I buy at Costco in bulk.

Incidentally, I had a whole case of Amsoil Fuel Injector Cleaner that I bought in San Antonio and used until I ran out (began giving some to my racing buddy with an RX-7).

Great stuff.

I want to change the gear oil to synthetic also, but that comes in December up in San Antonio.

salimshah

I wish you guys luck in doing a flush. But do get into it with both eyes open.

I have 'heard' that flush can be harmful, so do some reaserch to confirm or refute the myth.

Salim

TunedRX300

Salim, I believe power flush used by some shop is driven by some machine. The machine forces fluid in, vaccums fluid out, and stirs up old metal junk to wreck the tranny. What Amsoil suggested is pretty non-invasive, which coincides with my thought of opening the tranny cooler line and use tranny's own circulation system to pump out old fluid. I heard that the pressure to the cooler is only 4-6 psi, you can stop the flow by block the hose with your finger and won't be forceful to stir up anything more its usual operation. Well, at least that is the theory, Lexmex will be the guinea pig and hopefully live to tell us the result