transmission slipping???

97 Jetta GLS Automatic - Here is another problem I am having - usually happens when the car is cold and I first start driving it - I step on the gas but the engine just "revs" high on the rpms and doesn't really go anywhere - gets better the more I drive. Is my transmission done or what?

When was the last time it was serviced? It doesn't have a dipstick so it is difficult to check fluid level.

I took it into the dealer about a month ago to have it serviced. They ran a diagnostics test which came back negative and filled the transmission fluid which was low. But I'm still having this problem???? Is the transmission going???? How long can I drive it until it goes???
Thnaks.

If you're planning on having it rebuilt do it now as the longer you drive it the more expensinve it is likely to be. If you are just going to replace it with another unit then it will last a little whle (can't say how long), but eventually will slip all the time.