Quote:
Originally Posted by Wardbird
I am not sure I have ever understood the sealed forever transmission idea. While trans fluid will/can last a long time I think AuSeeker is right here. Speaking as a person with a degree in aerospace engineering, who has spent many years in and around the firearm industry as well, it strikes me that it doesn't take a rocket scientist to know that no fluid is made to last forever.
The simple laws of thermodynamics over a time of, cycles of heat and cold, natural condensation, natural wear and tear, suggest that there's a limit to any lubricity material.
Toyota may be right that flushing systems might not be needed. Perhaps there are a lot of these quick-change places that unnecessarily talk people into flushing systems, and they may in fact do more harm than good. But to suggest that the alternative is never change seems extreme.
I would think the best alternative is draining and refilling. Some do it a few times in a row.
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I can't cite a source but I read a while back that calling a fluid "lifetime" excuses manufacturers from paying a fluid disposal fee imposed on imported vehicles. So it's much easier to understand if "lifetime" really means "long enough that we won't have to fix the transmission when the fluid craps out or pay this environmental tax to get rid of the used fluid."
What you and others have said is right and it's simply common sense - no fluid, no matter what it's made of (and there's no evidence that WS is anything special) can indefinitely sustain its lubrication and protective properties, especially in a complex, high-heat mechanism like a transmission.
And besides,
Scotty says change it and, in his inimitable way, explains why.
