XhyDra

iTrader: (8)

WS Transmission Fluid according to what I've read so far, was only so that regular run of the mill shops wouldn't get their hands on newer transmissions with less of a chance of them damaging them with incorrect fills.

Now based on what was fact before about the IS not having cooling lines that could be used to flush the system, other car manufacturers did have direct cooling lines on their newer models, hence being able to restore the old with new.

This is just forum talk but I've read on several Toyota and Mercedes forums about WS Oil transmissions having slipping issues after high mileage and rather heavy uncertainty of wether running the transmission fluid for the life of the vehicle being a good thing. Now with the method described above being possible now, I believe fluid flushes should be a standard maintenance.

I'm not saying what the original car designers planned was a bad thing but judging from some high mileage IS's, transmission slippage is a growing concern for me as I'm sure it will be for many others. After reading several posts on other regular car forums about some IS's having transmission issues in what would be considered the high prime 100k or so, I would be highly inclined to have this service performed.

With that said I'm coming in close to 100k and I can say that the transmission doesn't feel as smooth as it once did and sometimes it lags or holds back on gears and jerks, nothing that would be considered failing by any terms, but it certainly feels like age is catching up on it.

If what the OP says about restored smoothness results from this I don't see how this could be a bad thing.