Prius Tranny Fluid

[green4evr2003]

Does anyone out there have any idea what kind of lubricant is used in the '04 Prius transmission? My neighbor the gearhead (40 years' experience as a pinsetter mechanic plus automotive do it yourselfer) is a strong believer in the efficacy of synthetic lubricants. Has anyone considered replacing Toyota factory original tranny lubricant with synthetic? Actually, my neighbor has said that even if a gearbox is originally filled with synthetic fluid, the fluid should be changed after an initial wear-in period because there will undoubtedly (based on his experience) be metal particles circulating in the fluid.

Bruce Webster 1/30

[htmlspinnr]

For '04, it's ATF type WS (4 qts), a low viscosity type ATF. Previous generation used ATF Type T-IV.

While I could be incorrect, I believe our transmission is mostly maintenance free, as I don't see any reference in the RM, NCF, or anywhere else about replacing the ATF during maintenance.

-Rick

[green4evr2003]

Thanks for the prompt reply. Per my previous post, based on my neighbor's experience, I believe there is no such thing as a maintenance-free gearbox. I'll bet that if one were to drain the oil out of the Prius tranny after, say 25, 000 miles, the fluid woud look like metalflake paint. My neighbor has seen that on every gearbox with which he has dealt, which is why he is convinced that synthetic lubricants are the way to go. Of course if changing the fluid on the Prius tranny is a major deal, then perhaps it is best left alone. Even though my '97 Saturn is a stoneage car, the transmission fluid is changed using a drain plug. The tranny filter screws on/off...just like an oil filter. But then on my '02 Saturn VUE there is no provision for either an easy tranny fluid level check (no dip stick) or for an easy fluid fill. Now, I have to get real and state that truthfully, outside of the gearcases (transmission, transfer case, and differentials) on the '85 AMC 4wd Eagle that I owned briefly, I have never used synthetic lubricant.

Bruce Webster

[Jerry P]

The Prius 'transmission' isn't very big...about 5 inches in diameter and, I have been told, uses about 5 oz. of fluid for lubrication. I agree that it would make sense to change it after a few 'wear-in' miles, though I can't find any reference that this is necessary. The metal used for the planetary gearset must be some incredibly tough stuff - they are SO small and handle all of the power transmissions of the car. In the spring ( which at this point looks like it may NEVER come!) I want to get under the car and really see where everything is. The great cut-away exhibit at Detroit gave me a good start. I got a really good understanding of the 1.5L ICE from spending a lot of time on the Echofans.net site. The young kids over there dug up everything you could possibly want to know about this fantastic, efficient little engine, so I feel I only have to get into the electrical part of the Hybrid Synergy Drive.

I think every Prius owner should get familiar with the drive system. It is the heart of the Prius and the thing that makes it better than anything else on the road today. To know it is to love it....

[efusco]

Originally posted by green4evr2003
Does anyone out there have any idea what kind of lubricant is used in the '04 Prius transmission?  My neighbor the gearhead (40 years' experience as a pinsetter mechanic plus automotive do it yourselfer) is a strong believer in the efficacy of synthetic lubricants.  Has anyone considered replacing Toyota factory original tranny lubricant with synthetic?  Actually, my neighbor has said that even if a gearbox is originally filled with synthetic fluid, the fluid should be changed after an initial wear-in period because there will undoubtedly (based on his experience) be metal particles circulating in the fluid.

Bruce Webster 1/30

All due respect to your friend I suspect his knowledge about the hybrid ECVT/planetary gear system and it's wear and maintainence characteristics is practially nil. In fact I know his knowledge about the '04 system is zilch. I'm sure his experience with traditional trannies would lead him to the conclusion you mention, and I'm sure there is some particulate/metalic wear showing in the fluid, there's no way one can empircally conclude that the fluid should be changed early or ever.

I think that after the first few Prii that travel 100-150K miles and need the ECVT looked at and if then they show abnormal or unexpected wear or they start seeing failures THEN Toyota may begin suggesting specific lube changes for that part. I don't/didn't have a Classic Prius, but I've been watching the YG board for about a year now and have never seen a reference to a ECVT failure due to wear (or anything else for that matter).

Perhaps your friend will, ultimately, be shown to be correct in his speculations, perhaps not, but he certainly can't make any factual statements in that regard based on evidence with this vehicle.

[htmlspinnr]

I'm inclined to concur with Evan.

The Prius planetary gearset has no clutches like in a conventional automatic, nor does it contain the dogteeth gears or syncromeshes of a manual tranny which wear over time due to engaging and disengaging.

As for the total amount, the RM does mention 4 quarts, however this lube also covers the chain and the differential. There is a pump as well, but I didn't see any mention of a filter.

-Rick

[green4evr2003]

'Nuff said. I guess I'll just let the expression "If it aint broke, dont fix it" apply. I appreciate all the advice. Just one more attempt at getting in the last word, however...How good this guy is with vehicles can be seen from the fact that as a result of his tinkering, he has never had a problem with the calipers on his old Ford Explorer (or any other vehicle since his old Volare wagon). In addition, he was able to figure out why the valve covers on his V-6 Ford Bronco leaked and to fix the problem.

Im case anyone is wondering why I'm dating my posts, I've recently seen a couple responses to my three week-old posts on the "2004-Prius" Yahoo page.

Bruce Webster 1/31

[htmlspinnr]

Not that I want last word - it still doesn't apply. I was a tinkerer myself, doing most of my own work on my first 3 cars (don't have a garage anymore or I'd still be doing it).

However, if he is good - let him study your Prius for a bit - then he'll understand how different it really is in many respects.

Prius really is a revolution in powertrain design.

[green4evr2003]

Forget the tranny...this is better. Since our garage has been full of camping gear, Girl Scout stuff, and miscellaneous other things more or less for the last...20 years, I have not put a car in there since probably around 1980. Since we also have a pop-up trailer parked at the bottom of our relatively steep driveway (long, off topic) and a relatively decent parking spot in front of the house, the cars stay up front and in the weather.

Bruce Webster 1/31

[Danny]

Just an FYI, the post date and time is kept in the database and above every post:

Example:

"Posted: 31 Jan 2004 03:57 pm"