Transmission drain/flush, how often.

From what I have read, most recommend an initial drain and refill at 30K. Then another drain and refill every 60K thereafter. Flushing is not recommended or required. I did my first at 97K and the second at 170K. Toyota says it is lifetime fluid. There are plenty of threads concerning transmission and fluid changes you can search up and read.

 

At least once every 60K. Simple drain and refill. Don't forget to replace the crush washers and open the fill opening FIRST BEFORE you drain the fluid...

Use the Toyota WS Fluid for best results. 4 quarts is all you need. A funnel with a long hose on it will help. Or you can pump it if you have a pump for fluids. You can buy the fluid at the parts dept. of your local Toyota dealer.

Patrick Wong posted details on how to DIY this job. Google search and you will find it.

Best of luck to you,
Ron (dorunron)

 

I would go a step further and say ONLY use Toyota WS fluid......lots of stories from people who decided not to.

Definitely not a lifetime fluid either as suggested above.

 

And what happened to the people who decided not to?

 

The few that have done it, and the fewer that have reported on it (i.e. Bob Wilson) showed abnormal copper content in the oil analysis. Remember that in a "normal" car, the ATF is just sloshing around metal parts. In the Prius is has this duty as well as being subjected to the high voltage and high EMF that MG1 and MG2 make. Toyota makes darn sure that their WS fluid is electrically non-conductive even with 500V flowing through it. On the Lexus line they have "sport modes" which can boost the voltage to 650VDC or more. It is a different ballgame when you subject solutions with suspended particulates and various blends to high voltage and high magnetic fields. Things can separate that shouldn't or otherwise wouldn't or things can get changed and become different solutions which can be more caustic to the system.

Since the Toyota WS fluid is so darn cheap, and the cost of a failed experiment is a new transaxle, it makes sense to just go with the status quo on this one unless you are OK with the thought of replacing the transaxle if you fail to pick a proper replacement to save $5 in fluids.

 

X2

For the amount you might save, it's totally not worth the risk.

 

Lots of posts with people using many different brands of trans fluid including Walmart fluid and no one on this site has reported any issue caused by the type or brand of fluid used. It's a non issue.

Except Bob Wilson who at that time was using a brand of Amsoil that had a known copper leaching issue.
It was in his G1 if memory serves. That was 6 years ago.

And how does Toyota make "darn sure" there fluid is non conductive? Please show me even the slightest bit of documentation on that formula. Even if they did that's pretty moot real fast the minute there is any metal wear in solution. When you pull used fluid that's dark or even black that's metal wear in the fluid. Nothing more conductive than that. Which doesn't really matter as there is no exposure to high voltage inside the trans. If there was that's called winding failure and you won't go far if the winding is exposed to the fluid.
That's a high voltage ground fault leak and will throw a code instantly.

I have aftermarket fluid in my car 7 years now. Pulled multiple UOA's and only thing I see is excellent wear numbers.

 

Some after market fluids are superior to WS and cost alot more. There is a better product out there then WS and has nothing to do with its "dielectric properties" which WS has none.

I'm using 100% Synthetic fluid which WS is not synthetic.

Amazon.com: Customer Reviews: Red Line 30504 D4 Automatic Transmission Fluid - 1 Quart

 

If you want to roll the dice on your vehicle, be my guest.

 

Yeah its a dice roll......cause of all the high voltage in there.

7 years of throws so far.

Hey I put my money where my mouth is. I pulled UOA's and there in the trans sticky.
Almost zero wear over 30K mile runs on it. And there is no dielectric test on trans fluid so I don't bother asking not to embarrass myself.

They save that for transformer fluid. That's never exposed to gear wear.

 

Back on track, best guess is at 30,000 miles, then every 60,000 miles. Unless you know more than Toyota does, or want to learn more than Toyota is telling us, use ATF WS.

(It is possible that with the results we are building up, the final best recommendation will be 30,000, then 90,000, then every 90,000)

 

I have had it done twice at my Toyota dealership, about $110

 

Toyota is telling me and I quote from the Owners manual:

Use Toyota WS or equivalent.

Toyota is well aware that there fluid is not the space age stuff that you make it out to be. Its just low viscosity 10 weight fluid used in a wide range of Toyota vehicles including there non hybrid trucks. Not even synthetic.

 

Ed, how does someone determine what the equivalent of Toyota's WS is? (Or Toyota's Super Long Life Coolant, for that matter.)

TIA.

 

Dolj seeing the posts above reminds me of the old saying, "being the loudest person in the room does not make you right". It´s a free world and it´s up to you who's advice you take, but again in most cases as a former professional auto mechanic I have to agree to disagree with the view above to the contrary and instead suggest using both the Toyota coolant and transmission fluid in your Prius. The engine oil is where you get more leway IMHO but I certainly favour synthetic over conventional for obvious reasons.

 

Thanks MTL for your take on this subject. I like to think that I'm fairly open minded and all information is gladly received and considered. I don't mind using 3rd party products over the manufacturer (partly because in our market sometimes you have too), but I don't want to find myself in the situation where that product caused damage because it was not in fact functionally equivalent. This is where I find myself looking at product labels, only to find myself thinking that it does not tell me anything helpful to decide if I can use it or not. I'm not necessarily going to blindly accept the statement on the label that it can be used in all Toyotas just because it says so.

Ed said he used a 3rd party transmission fluid in his transaxle, so I thought he could share how he evaluated it to know it was equivalent to Toyota's WS. I know I for one would find that helpful.

Just to give an example, Toyota Super Long Life Coolant is NZ$58 (US$49) for 4 litres (4.23 US qt) here, so if I can find an after market for cheaper (which I can't ATM, the only possible contender is actually more expensive, if you can believe that) I'm happy to go with that.

 

Living outside of the US, I too am always looking for alternatives but you need to weigh the risk/reward for products you want to use as substitutes as you suggested.

If we were talking a standard hydraulic transmission, then sure there's lots of empirical evidence for alternatives to the WS fluid. Doing this right requires you to have the fluid tested to verify the actual fluid characteristics because manufacturers have certainly been known to stretch the truth and you also need to know how any differences will affect the durability or operation of the vehicle. Also aftermarket fluids often change their composition over time without warning due to price considerations (ie fluid bought one year to the next may not be the same thing in reality despite what the marketing says, motor oils moving from Type IV to Type III because it's cheaper are a great example of this). In such a case it may make sense to use since transmissions like the Tundra use ALOT of fluid for a flush and heavy towing may make fluid change intervals alot shorter as well. In an electro mechanical transmission there are more design considerations to think about (I'm not just talking voltage here as someone liked to allude to above) and the amount of fluid used is quite small so to sticking with WS makes sense even if it was not the cheapest option. The transmission on a Prius is very expensive to replace so consider carefully if you want to experiment with yours.

Cooling systems are another area people need to be careful with because the Toyota Super Long Life coolant contains both phosphate (short-term protection) and organic acid (long-term protection) technology which the Asian manufacturers tend to design for. So using the wrong coolant can affect things like pump cavitation, premature pitting of internal parts, etc. Again this is why I would stick with the Toyota coolant as well even if you find cheaper stuff and again it makes sense given the frequency of the changes required.

As far as motor oil is concerned that topic has been discussed on BITOG ad nauseum so as long as you understand what your requirements are I'm sure you can find engine oils that will work for you and your budget.