Pentosin is something special and it depends on your car design what you need, Pentosin or just ATF. For example I need Pentosin 7.1 and there is a sticker on the reservoir like this green one. You can also get Pentosin at VW and Mercedes Benz dealers.
Look at the sticker. Look in the reservoir, the pentosin is green the
ATF is red.
info on Pentosin