Given the high price and "lifetime" claim for WS atf I assumed it was synthetic. I bought some for a change and found a MSDS in the bottom of the box. The salient point: "mineral oil concentration by weight- 80-90%" To me this means dino oil. Viscosity is given as 23cSt@40c and 5.45cSt@100c. Make that really thin dino oil. The only synthetic I find in the marketplace that is recommended by it's maker for this application is Red Line D6 with a viscosity of 30.7cSt@40c and 6.4cSt@100c. Does anyone know of any other suitable synthetics?
You are talking about transaxle fluid for your Prius? In that case use the stuff recommended by Toyota. In the Prius it also serves to insulate and cool the MGs; do that wrong and you have a very expensive repair bill. Tom
The transaxle is a very expensive part to experiment with. ATF WS isn't expensive. Its about $30 for 4 quarts from the dealer. I change mine every 30k to 40k miles (about every two years). No problems. Its a simple DIY job. Remove and replace. Done. My last Toyota lasted 22 years before I sold it. I find simple preventative works best. Its cheaper NOT to experiment.
Synthetic or not synthetic is not the main concern. The main concern is whether the fluid is the proper one for the transmission. In this case, WS is the only fluid that has been tested to work correctly.
There is at least one person using D6, I think he finally published a good UOA result. I'm using WS on a 30k change schedule.
There may well be some fluids that would do the job just fine but as 6lark5 mentioned the transaxle is to expensive to experiment with. There are some fairly high voltages in the transaxle due to the two motor/generators. We do not know how well any of those other fluids would insulate. I have had two UOAs done and 30K seems to be a good change interval. Maybe the first change could be done a bit sooner.
Anybody know if Genuine Toyota ATF WS is actually made by these people (who claim WS is 100% synthetic) http://www.mitasuoil.com/en/fluid
Agreed. Every 30k miles is about every two years for me. At $32 every two years, I see no reason to experiment with any other fluid with this expensive transaxle with the MG's.
More conspiracy theories on BITOG, of course: Interesting Toyota WS ATF Research. - Bob Is The Oil Guy I don't know what to make of all this, except (1) there seem to be multiple worldwide suppliers of ATF WS and (2) synthetic or not, it is really good stuff.
I had a VW with a DSG transmission and the service is at every 40,000 miles. The dealers charge anywhere from $300 to $600 plus to do the service. For a do-it-yourselfer, about the cheapest I've found the maintenance parts alone is $129.00 plus shipping. You need a special tool to add the fluid and you also need something to monitor the fluid temperature during the service. I made the tool myself for around $10, but if you want to buy the official tool, I heard it's over $200 now. From what I've seen of the Prius trans, it's a piece of cake to service. Here's the kit for a DSG change. DSG Service Kit 40k - IDParts.com
Prius does not have a torque converter to generate high shear and heat, and it doesn't have to deal with the clutch wear particles. The only mechanical parts are gears and bearings. But insulation resistance of the oil could be a factor so don't deviate from specification!
ATF-WS is by no means expensive comparing to Honda's CVT fluid, which costs $16~20 in Canadian funds, for US Quarts. Also, I don't think there's anything inherantly better in a fluid being synthetic. Also, the conscensus around here is it's better to change it periodically, regardless of Toyo's claims.
Synthetics don't normally shear to a lower viscosity as fast as regular oil. For a "lifetime" oil there would be some advantage to that.
So the transaxle fluid is supposed to last for the life of the car according to Toyota and yet it's not synthetic? Or is only the original transaxle fluid synthetic and Toyota's recommended stuff (since it's meant to be replaced periodically) not synthetic?
