Some owners say never, and they’re not wrong! Here’s why.
If you buy and own a Toyota Prius, if you’re a good owner, invariably, you’re going to ask yourself if and when do you need to change the automatic transmission fluid.Embed from Getty Images
You take a peek at your warranty and maintenance guide and soon find out Toyota doesn’t specify transmission fluid change intervals, at all.
Toyota lists oil and oil filter changes every 10,000 miles, so, why not an ATF fluid change?
While Toyota websites recommends most vehicles change your automatic transmission fluid at least every 60,000 miles, the Prius is a special case.
In fact, Toyota’s brightest engineers, in writing up the Toyota Prius maintenance schedule, determined that the Toyota Prius automatic transmission does not require regular maintaining by way of automatic transmission fluid drain and refills.
The only “maintenance” required is a visual inspection of the automatic transmission for signs of leakage every 30,000 miles.
The only time Toyota specifies you should attempt an automatic transmission fluid change is if you’re “driving while towing, using a car-top carrier, or doing a lot of heavy vehicle loading (driving an extended period of time with a full load.)”
If you’re like 95 percent of Prius owners with regular driving habits, you don’t need to change the automatic transmission fluid.
Besides the aforementioned visual inspections, expect to never have to worry about the automatic transmission or ATF levels for the lifetime of your Prius.
Why is the Prius automatic transmission practically maintenance free?
The Toyota Prius transmission is practically maintenance free because Toyota has equipped your Prius with one of the most durable transmissions known to man.
You’ve probably noticed your Prius doesn’t make shift noises like a regular automatic.
That’s because the Prius uses a CVT, or a continuously variable transmission.
More specifically, Priuses have an eCVT or electronic continuously variable transmission.
“The eCVT found on the Toyota Prius and other hybrids differs from CVTs found in other vehicles, such as the 2013 Nissan Altima or 2012 Scion iQ, because it does not use a belt or chain connected to a pair of variable pulleys.“
“Instead, an eCVT uses electric motor/ generators to control the speeds of planetary gearset components. This allows the eCVT to continuously change the gear ratio, keeping the engine’s rpm in the sweet spot. “
If you’re the nerdy type and have half an hour, do yourself a favor and watch this eCVT teardown and explanation by Weber State University. It quickly becomes apparent these Toyota eCVTs are literally the most reliable transmissions in the world right now.
Because these eCVTs have far fewer parts compared to conventional automatics and manuals and because it’s an overengineered and robust design, Toyota engineers determined these eCVTs can be maintenance free.
Does the Prius have a transmission dip stick and, what if I want to change the Prius fluid just because?
According to Exclusively Hybrid, because the Prius’s eCVT is sealed and is supposed to have lifetime fluid, the Prius does not have a dipstick in or on the transmission.
That’s not to say you don’t have the right to check or change the fluid, it’s, after all, your Prius and you can do whatever you want to it.
You’re often buying a Prius from a first, second, or third owner, and you don’t know how rough they treat their cars so, it’s a good practice to “check” the eCVT fluid level to ease your mind and, while you’re under their, you might as well do a drain and refill.
A quick google around reveals a couple threads illustrating just how easy an eCVT drain and refill is.
As their DIYs illustrate, devoid of a dipstick, you’ll know when your ATF (or eCVT fluid) fluid is topped off when ATF starts pouring out of the fill hole.
My only recommendation, if you decide to do a drain and refill, is to use genuine Toyota ATF WS fluid and not a third-party fluid, this ensures you’re using the fluid the Prius was engineered for.
As mentioned, Toyota equipped your Prius with one of the best engineered transmissions ever made.
As long as you don’t notice any drips or wet spots around your Prius’s transmission casing or directly under it, you don’t have to ever worry about it.