Over the past several years I had noticed a gradual decrease in fuel efficiency in my 2010 Prius with 122K miles. I tried everything to get it to come up from the 43-45mpg range. I did everything people recommended, a wheel alignment, fuel injection cleaning, changing spark plugs and making sure there was at least 40lbs of air in the tires. I even had the traction battery pack tested. Everything checked good. After doing all of these things and spending $455 for the dealer to do a "driveability check" and tune-up, no improvement at all. It wasn't until I did a routine transmission fluid change did I notice a difference. I drained the transmission and examined the fluid. It looked a little darker than normal but didn't look bad. I refilled with 3 1/2 quarts of ATF-WS. The first few days, no noticable improvement. By the end of the first week, MPG had increased to 46.4. The second week, I was astounded when it went to 49.5! I said to myself, if it gets to 50, I'll be satisfied. Now, keeping in mind, this is city/hwy driving, same daily route, same temperatures and same driving conditions. By the end of the third week it became apparent that something had changed. By the end of the tankful it was 52.7 mpg, and has stayed in that range ever since. My advice is, don't wait till the 60, 70 or 80K interval before changing the ATF fluid. Do it every 30,000 miles!
There is no, Toyota prescribed, time to change the cvt fluid, just to 'inspect' it. Instead of going through all the hassle of inspecting it, just change it. Fifty bucks worth of new fluid and an hour of your time is well worth it if you value getting the most out of your Prius. Happy to read you're back up to advertised MPG's! Have you cleaned your EGR components?
Good story. The placebo effect is a powerful thing. Are you manually calculating your MPG figure......or looking at one of the displays ? There is NO good reason to think that your change of fluid actually had anything to do with your improved mileage.
There are so many variables which can influence your mileage that it is extremely hard to pinpoint a source of a change. Weather and traffic have a huge impact.
There is no variable in a gearbox, other than normal metal wear. So I doubt that changing the fluid in the "transmission" did anything at all to help your MPG.
I must agree with the others that this fluid change alone is very unlikely to be the whole cause of the improved MPG. Any MPG loss caused by the old fluid should have been small, if anything at all.
I didn't notice a mpg change after transaxle fluid change, but who knows: if it worked for you, that's what counts.
A few days go the pump I filled up was super slow. It was like filling on the first clip on the handle. It took forever to fill the tank. And I wasn't sure if it was really filled, or partially filled. My mpg was 36. It should have been around 44mpg. I just figured it was a bad handle. Today I filled up at it filled normally. It calculated out to 52mpg. I KNOW that is NOT correct. I'm thinking it will go back to normal when I fill up Friday.... So maybe where you filled up the handle clicked later so more fuel than normal was put in????
I had similar effect. My ATF was changed at our meet ups with the help of raytheeagle, I was able to finish my regular drives home with 4 bars instead of 3 on the HV bat on a consistent basis. Same weather conditions and tire pressure; 44psi on all 4s. Not everyone may yield the same, or similar results. YMMV
Sounds like it over-filled a bit the first time. That would drop your calculated mpg. Then the next fillup was less, due to the previous overfill, which raises you calc'd mpg. What this illustrates, is even with variations in fill technique, it invariably balances out over multiple fills.
For some reason, the pump was slow. It just kept going. I was waiting for it to start overflowing, but it didn't. It would have kept going, but I decided to stop it. I did report it to the state. Nice when they put the phone number on the pump! I'm sure it will be back to normal on Friday's fill up...
The disc covering the fuel opening broke on my car a few years ago. If I want I can get another two gallons in the tank after the first click. I have to hold the nozzle in the cup. not inserted in the opening. Most don't realize that speed of the flow, different pump, depth of the nozzle while filling will make a difference in how much fuel you can squeeze in the tank.
Normal fill up today. I figured it would be. I know when you fill slow it splashes around a lot so it doesn't completely fill. The pump I used has been good, except for the time. Depending on the price, if I stop at that station, I will use a different pump. Give them a few weeks to fix it.
I changed my ATF a couple years ago and my MPG stayed the same in the low-mid 40s. My MPGs are low because I sit in LA traffic... fun times indeed.
