Toyota switched at the end of the 2003 model year from IV ATF to WS ATF in the new 5speed transmission they are using in the Landcruiser/LX470/GX470 and 4runner. Does anyone know what is the difference in the two fluids? What happens if they are mixed? What is the cost difference? Toyota claims that if you don't tow that you never need to change this new WS ATF fluid (I question that but don't know what this new stuff is). Any information you could give me on this new fluid would be appreciated.

 

Do a search on WS ATF, there were several threads on this as I remember.
In short, Toyota does not recommend mixing the fluids. As for their suggestion that the fluid doesn't have to be changed for 100K, I wouldn't let my trans go that far. One small problem though, along with the fluid change, Toyota removed the dip stick and tube from the trans. In order to check the fluid level, you have to use a 'sight' plug on the side of the trans, like the standards. You can still drain the trans (partially) by removing the sump pan and then refill it through the 'sight' plug, it just is more difficult. PROGRESS :wtf:

 

I agree with you Tech, I plan on changing it at 50K miles even though I don't tow, or drive under severe conditions. Couple of reasons I will have it serviced at 50K miles. One I am to old and can't let any transmission I own go to 100K miles before servicing it. Two, I want it serviced 10K miles before the 60K mile warranty is up incase a problem comes up. I will be trading at around 90K miles so I think I should be OK. Plus when I have it serviced by the Toyota dealer, I will make sure everyone from the service writer to the guy that works on it knows it uses the WS fluid and not to mix it.