No transmission oil change intervals?

I can't blame you for questioning the appropriateness of the "maintenance schedule" advice.

Based of my experience with my 2018 Prime, I had the trans-axle fluid changed at 50,000 kms and it looked pretty bad when compared to fresh Toyota fluid. The fluid replacement was not expensive and since I drive in EV 99.9% of the time, I see it as a excellent insurance and piece of mind.

Because it was that dirty, I made a commitment to have it changed every 50K at the latest. No exceptions for either of my Primes, including the newer models.

Cheers

 

Toyota says you don't have to change the transaxle fluid but many people say that the initial change shows dark fluid.

Is it possible that the assembly lube used at the factory is a weird color that makes the fluid dark? Has anyone had that first-change fluid analyzed to see if it's contaminated with bad things?

Ed

 

Any oil will turn dark after a short time of use and heat -- it does not indicate that it is bad.

 

Very true Indeed.

Except in my case the heat component is questionable. At its highest point during the summer months, the "trans axle" temp never goes above 40c while the average throughout the year is closer to 10c. One could also say, I take it easy on the cars with relatively conservative driving routines.

Cheers

 

Is that what you've learned from datalogging? That's very interesting. Not really surprising though given that the Prius "transmission" does very little work. And by that I mean, there is very little energy being turned into heat in the transmission - which tells me there's even less need to replace the gearbox oil on a regular basis.

 

I’d agree, but a very logarithmic schedule is worth consideration, say one change at 10k miles, and a second (and likely last) change around 100k.

 

Agreed, but when running in EV you only have something like 27 horsepower -- coming from highly efficient electric motors.

 

When I changed out the tranny fluid in the 2017 Prius, it looked very clean, not dark at all. She only had 28,000 miles but was at the 6-year point. I, also, drained and filled the coolant and transaxle fluids which takes the same same Toyota WS coolant so very easy.

Of all the cars I've owned, this Prius has been the easiest for maintenance (far easier than my 4x4 Tundra with the differentials and the lube job and the transmission fluid change procedures)....hardest thing on the Prius was actually breaking the drain bolts from the transmission...on there pretty snug!!!

 

The Prius transmissions have some planetary gears, but quite a bit of it is not I believe, according to tear down videos, much is regular helical gears meshing. Gen 2 has a chain as well.
Most United States made auto transmissions starting about 1940 were all planetary gear sets with clutches and torque converters. They too could last a very long time. But a lot didn’t, clutches and heat I suppose. Also fluids were improved.
Hydramatic - Wikipedia