ATF fluid changes ARE Required.

I even reuse the oil plug washer, 100k miles no leaks

 

An aluminum crush washer is an annealed solid aluminum washer. The Toyota washers are crush washers. The main reason they say to not reuse them is because they harden when they are used and can't be annealed like soft solid copper washers could. If you are a little lucky they can be reused several times, if you are not a little lucky you will have a leak at a drain plug on a transmission full of oil. You can change the leaking washer without loosing much oil but it's a nuisance. It makes no difference to me what you do, but some people came here for advice and should leave aware of the correct way to do a job and an awareness of the potential problems with shortcuts.

 

If they are generic 18mm washers, I have a 50-pack of them on my desk that I bought for $9.

 

If there was a leak you would notice in your garage or driveway

 

Yes, there is a hole in the engine under cover below the drain and fill plugs so you would see what dripped out.

 

Just finished my Prius 2011 - ATF change. I have 26,000 miles.
Everyone was spot on with info here, even the thick opaque burgundy color of the ATF from the earlier pic I saw.
I would like to emphasize two things.

Drop the belly plastic tray with the oil door and have extra plastic pins for the tray. I broke a few, they dry rot or become brittle. The car is not garaged.

One more note I forgot to do, per the instructions, is check the fluid level after you drive it a little.

Great tip from here: Always remove fill plug first. (BTW, my two plugs do not contain magnets.)

Also I am adding a pic because I dislike those black and white Toyota pdf files for instructions.
It got messy because I used an electric 12v little pump and the hose slipped out and splashed everywhere, while filling.

 

Way better pic

 

Where you able to capture a sample in a clean, dry, water bottle or sample container?

I've had two changes:

• 5,000 mile (5k service) - still clear, it had metal debris and bits of sealant
• 20,000 mile (15k service) - still clear but I didn't get a large enough sample to send for testing (Toyota service center failed my request)

The car is just under 40,000 miles and I'm not sure when I'll do the 3d change but I'm leaning towards 50,000 miles (30k service). The reason is the 5k change suggested a straight-line viscosity loss to 15% would happen after 15k service miles. That is why I was so pissed when the Toyota Service Center gave me two tablespoons of used oil in the water bottle. I'm still working on the initial oil lasting 15k but I don't know how long it can go.

So my thinking is give it 30k service miles and then properly sample and have it tested. It it has gone beyond the 15% viscosity loss, we'll know this is the upper limit. If not or still within bounds, we're OK and will adjust the expected oil service interval appropriately.

Bob Wilson

 

I did not capture any clean ATF. I was just glad I got it done.
I decided going forward to follow a 30k change to give me a piece of mind.
It was easy and I know what to expect next time. Note: I will get new washers at 60k.

 

Everyone makes a big deal from that single fact of burgundy color of used WS while it may mean nothing. I noticed long time ago, if you spill WS and expose it to direct sunlight, it turns into burgundy/purple color within a couple of hours. This could be just a function of the specific pigment used in WS.

Nice picture BTW, thanks.

 

I completely agree: take the whole panel off. At least, I think that's what you're saying. And, part of the problem with the clips breaking: might be that they're accumulate grit, locking up the mechanism. Everytime I have them off I wash them, flush the grit out.

I did do that, but found it was just as I'd left it, ie: the transaxle didn't absorb it anywhere. I resolved to not bother with that next time.

 

I understand what you are saying but mine was a very deep, dark burgandy color right out of the drain plug. I remember getting a cup of the new WS fluid to compare while letting the transaxle complete draining. This is with the drain pan underneath the car without exposure to sunlight. The old fluid was many times darker than the new WS. I would describe it as a dark, red wine compared to pink koolaid (sp?).

 

Bill, have you thought about the fact that your transmission has extremely large powerful permenant magnets in the two electric motors in your transaxle that are going remove any ferrous metal from the fluid?

 

Guys, Toyota didn't drop the ball by accident. Every manufacter designs failor into vehicles. How long do you think a company could stay in business if they didn't design there vehicles to fail. With the advanced oil of today and the advanced engines and drive trains they still have to design failor rates into the vehicles and a lot manufactors and choosing to used sealed for life transmissions to do that. At least that is how they sell it to the public who wants low maintence cars. They tell them there is no need to ever change your transmission fluid.

 

The parts manufacter for Toyota that supplies the transaxle for the Prius also supplies to the Nissian Altima Hybrid and Ford Escape hybrid 2005-2012 and fusion hybrid 2010-2012. Ford used there Mercon V in the transaxle's until 2009 when it switched to Mercon LV (low viscosisty) and Nissian uses there automatic transmisssion fluid and Toyoto uses World Service. Same transmission. You could poor what ever transmission fluid you wanted into your toyota and it would be just fine. Just change is every 30,000 miles.

 

30K miles is a good interval based on our UOA data. However I will continue to use Toyota WS due to the Voltages present in the transaxle, up to 650V, and we are not sure of the electrical characteristics of the other transmission fluids.

 

So this morning, we had one of those increasingly rare, sub-freezing nights. I repeated my hill roll-down test:


The Prius temperature gauge showed 34F. By the time it reached the stop sign, the cold-soaked, engine-off, "N" car was at 15 mph (GPS). In effect, the car rolled down the hill achieving speeds equal to a warm car.

So here are the changes:

• Type WS - it is on the third change with just about 30k service miles.
• Largest diameter tires - the front pair are the largest that fit in the wheel and the rear pair, the next largest. The largest diameter tires are 6% slower turning. Originally installed on the front to improve straight-line stability, it looks like they may also make a detectable reduction in stirring losses in the transmission.

I am sympathetic to those who want to reduce wear on the gears with a more viscous ATF oil. But in my case, I consider heat to be the enemy and the lower viscosity oil will have lower stirring losses leading to a cooler running transmission. Now this may lead to an early bushing or gear failure but I'm OK with this risk because we know this transmission is subject to MG2 stator burn-out. For me, heat is the enemy.

There may be lighter viscosity ATF oils than Type WS. The closest I could find were aviation turbine oils but they were no better than Type WS. No, I'm not interested in substituting engine motor oils as I've already achieved my performance goal ... minimum transmission temperature and lowest possible rolling drag.

Bob Wilson

 

I don't know, seeing the fluid this way, to me, would indicate contamination. Much in the same way when I ran my four-wheeler through a few bogs, the crankcase oil went from clearish to opaque. Perhaps the Prius trans-axle is not as sealed as we expect?

 

I tell you what, find me an example of automotive oil of any type that conducts electric current and I pay you $100 bucks.