Toyota service center and not servicing as per Toyota schedule

they often write, 'customer refuses xyz service', but idk if they always do. either way, it's good that you're doing it.
i think your tranny will be fine, without a test, it's hard to know the condition of the fluid, and in north america, they don't even recommend changing it. they call it 'lifetime'

how many km on her?

 

What are those recommended intervals in your country? They don't specify any interval for transmission oil changes in the USA. That's controversial, though.

 

It would be helpful to know what the maintenance schedule is for your car.

In the US market, the Gen2 schedule shows engine and inverter coolant change at 100.000 miles, and spark plugs at 120.000 miles. There is no listing for transmission or brake fluid.

Posted via the PriusChat mobile app.

 

It is highly unlikely changing your transaxle oil made it more responsive or your engine stop starts smoother. There are no hydraulic actuators, clutches or gear shifting/engaging in the transaxle of a Prius. The oil does lubricate planetary gears which are constantly engaged and helps cool the electric motors. Which is why the fluid is considered lifetime by Toyota in the US. On the other hand, changing can't hurt UNLESS the wrong fluid was used which potentially could impact the motors.

 

That’s a Toyota publication, saying 4 years or 60k kms for “transmission oil”, specifically for Prius?

North American Toyota schedules make zero mention of transaxle fluid change. FWIW, I’d recommend a first change around 16k kms or 12 months. Then one more, around maybe 60k.

 

Hybrid transmission is like differential, all gears and magnet, drain and refill 99.99% got changed. The recommendation is 60-100k miles for the ATF in hybrid but it is not as critical as torque converter type transmission. Just change it every 60k miles if we do towing and carrying 4 passengers all the time.
As most Prius owners in North America, we concern more about oil consumption and 5k miles interval is still the most important thing here. No one ever have transmission problem in Prius 3rd gen, but millions with oil consumption.
Toyota WS and Dexron VI are very similar in the characteristics and Tesla uses Dexron VI for its transmission. Some people in BITOG stated Dexron VI has better characteristics standard and licensed to other brands. Toyota WS is not licensed to others but often can be substituted by DexronVI fluid like Valvoline Maxlife Dex/Merc, Dexron VI supertech, etc. if you cannot find WS fluid.

 

One thing: Toyota Canada maintenance schedule for our 2010 Prius is a single document used to describe the requirements for ALL their vehicles. Accordingly it’s almost unreadable; mentioning every service for every vehicle, with various caveats and exclusions, mentions of four wheel drive fluids, conventional transmissions and so on.

To understand how it applies to a specific vehicle almost necessitates a rewrite, preferably in table format, say with months/miles columns and description rows.

IF your schedule is similar, applies to multiple Toyota vehicles, perhaps the transmission fluid change was applicable to another vehicle??

again I’m firmly in the change it camp, just a little incredulous that Toyota broke their usual silence on Prius transaxle fluid.

 

There is little doubt that fresh fluid in the transaxle will largely remove any contaminates that may be floating around. On the other hand, Toyota developed the Prius largely to meet a California regulation for a near zero emissions, high mile per gallon, low carbon vehicle. Part of that thinking was extended 10 k mile oil changes and no transaxle fluids replacement reduces the amount of hydrocarbons used by 50%. It became cool to have a Prius when fuel prices doubled and the rest is history.

 

The oil, fluid, coolant and filter prices have stabilized and are actually being discounted in the US recently. It is hard to say gen3 Prius reliability issues have anything to do with oil change frequency.

Some manufacturer's vehicles have intervals of 15k miles. The gen3 Prii have bad engineering causing reliability problems, starting with flawed pistons, rings, pcv and egr designs. The engine was significantly redesigned for the gen4s to resolve all these issues plus benefit from improved cylinder cooling strategies and revised head gasket geometry. Fluids are the same in gen4s as are the extended intervals but the redesigned engines are showing vastly improved reliability.

Most of us believe increased oil changes in gen3s "may" keep the flawed rings free longer. Interestingly, the gen3 transaxles are reliable even with no fluid changes in the US.