When to change transmission fluids, etc

Others will comment on the ATF. As for the cabin air filter: change it or vacuum it if it's dirty. You can easily do this yourself in five minutes. A new one should cost about $21 at the dealer's parts counter.

 

Uhh, I thought it comes at 100,000 miles? I don't have the maintenance guide at hand.

 

I believe it's 100,000 miles for transmission fluid. Or I sure HOPE that's it because I'm not even looking until then.

I change the air filter every 20,000 miles, needed or not. Cabin filter has been 30,000....

 

Our testing data suggests the NHW20 in non-dusty environments need to have the transaxle oil changed at ~60k miles. Art's Automotive suggests 30k miles which is OK by me too. In dusty, rural areas, I would go with 30k.

For the older NHW11, I would go with 30k for non-dusty areas and a little as 15k for dusty areas. Again, this is based upon transaxle oil test results. However, it is your vehicle.

If you do have it changed, I would recommend bringing a clean, dry water bottle, about 1 cup, and have a sample taken. If it smells burnt or shows a very dark color, you may want to have it tested to see how badly it was worn. About 15% of the old oil remains in the transmission after a change so this may shorten the time you go before another change.

Testing needs to cover 40C and 100C viscosity and the viscosity index. This is your primary wear indicator. The secondary wear materials and particulate counts are useful but not nearly as much as the two temperature viscosity measurements.

Bob Wilson

 

Hi Jared,

I agree with Bob that periodic transaxle fluid changes are appropriate to help extend the service life of this very expensive part. I change the fluid on my 2004 at 30K mile intervals.

Note that "differential" and "automatic transmission" are one and the same as far as Prius is concerned. The 2G transaxle requires 4 qts of Toyota ATF WS fluid.

Regarding the cabin air filter, since you are breathing the air that passes through the filter you might be motivated to change it from time to time. I suggest that you remove it and see how dirty it is. If it hasn't been changed over the last 20K miles or more, it will probably have a disgusting amount of debris on it.

 

That's your decision. However note that for marketing reasons Toyota might suggest the minimum necessary maintenance so that the car will reach 100K miles without undue mechanical problems. If you are interested in having your car last longer than 100K miles, then you may choose to have more service performed than the bare minimum. A transaxle fluid change will not hurt the car, and may help its ultimate longevity...

In my case a transaxle fluid change costs me $20 for the fluid, $2 for the drain and fill plug washers, plus 1/2 hour of my time - so this is not a big investment. If your mechanic wants $100 for the service I can see why you might think twice.

 

Jared, there are a lot of discussions on auto forums about the freqency of changing various fluids on cars. Many manufacturers have started calling the transmission and differential fluids "lifetime" fluids. This of course begs the question of what is a "lifetime"? My personal feeling is that, in general, there will not be many failures of these devices in less than 100k, and if it does fail after 100k, the dealer will just say that "things break". However, testing of transmission and differential fluids shows that they have severly degraded by 50-60k. After that point, the poor quality of the lubricant is shortening the life of those components. Although, they will still probably go well over 100k.

It is very reasonable to change the fluid now.

 

On of the really big advantages of being on PriusChat is there is some good information obtained by many who have had their oils and fluids sampled and tested. The following advice is based on some actual measurements. (e.g. See bwilson4web entries on Transaxle Fluid).

The one thing that has been discovered is that the transaxle fluid can degrade more than expected in some vehicles in some driving conditions. As a result, most all the PriusChat members who want their vehicles to last to >200,000 miles and maintain their own vehicles agree with the 60k change on the Gen 2 Prius. However, going 100000 miles is not much of a risk and I have yet to hear of a Gen 2 failure caused by bad transaxle fluid.

 

[Oops! Curse my rotting memory, and thanks to Patrick Wong for the correction.]

 

The transmission and differential fluid are the same thing. The differential is located within the transaxle case. The fact that they are listed separately is evidence that tremendous thought is not given to the published maintenance schedule, which is why I suggest using it as a guideline. It is not like the word of God.

Here's another example of an incorrect item from the 2004 maintenance schedule:
Toyota Parts and Service

"Inspect the following:
...
Radiator, condenser and intercooler"

Last time I checked, Prius does not have a turbocharger or supercharger, hence there is no intercooler.

 

I hope you're right about earning points, but in my experience the guys at the shop will just think you're nuts.

Here's a story: I recently went to a Ford dealer buy some ATF for my 06 FEH. Ford no longer makes the 'Mercon' type fluid and it's been replaced by something newer, but the parts guy didn't know what kind and didn't have a reference book. He said "bring the car over and I'll look at the dipstick." Um, the car doesn't even have a dipstick on the transmission! (The FEH CVT is much like the Prius CVT, only a fill plug and drain plug...) I ended up talking to someone else.

 

What ATF fluid is used for the FEH? I am wondering whether this fluid is similar to Toyota ATF T-IV (used in Classic), or Toyota ATF WS (used in 2G).

 

Toyota ATF WS

 

I'll be the first to admit that Toyota does a poor job proofing their manuals. They also tend to throw in a lot of generic crap that is impossible to do on a Prius anyway. For example: "lube the chassis"

I've been looking 4 years now, have yet to find a single zerk on my Prius

The humorous proofing and somewhat odd habits carry over to other Toyota's as well. I also have an FJ. The owner manual, factory shop manual, and maintenance guide are pretty clear the transfer case is to only use a 75W-90 GL-3 gear oil.

GL-3 is an obsolete spec that has not been used since the early 1980's. So I use GL-5 as the closest substitute

Even worse is the weird gear oil specs for the rear axle on my FJ. Toyota claims to *only* use a straight 90 gear oil. Where exactly in North America does one find a straight 90 gear oil? Some FJ owners have received flak from the dealership and even Toyota corp. for using a 75W-90, one dealership in Hawaii even stated on the service order "synthetic gear oil used, warranty VOID"

Except last November, Toyota suddenly issued a TSB on the FJ. Apparently, the only gear oil to use in the FJ is a special Toyota synthetic 75W-85.

Hmmmm

Where *exactly* does one find a 75W-85 gear oil in North America? Oh right, the same Toyota dealership that prior to Nov of 2007 was warning their customers that use of a synthetic gear oil voided the warranty

Long story short: there is no separate fluid for the "differential" all are in the same case. I can post pictures from the manual to prove it. As far as changing the fluids, I did the cvt at 12,000 km and it was pretty dark. Subsequent changes have been much clearer, so I'll keep that practice up.

It's fairly easy to change the cvt fluid in a Prius. If your dealership tells you that you need to "drop the pan and change the filter" smack them, they are full of s***