This is what I googled and saved a while back, but while in Spain having van looked at for a recall by a fiat workshop, he topped up my oil, it could have been anything for all I know.https://www.pli-petronas.com/uk/products/passenger-car-oil/petronas-selenia/selenia-wr-forward
This is what should be used or your warranty could be affected.
Main dealer price is actually very reasonable, i got a 2l tin for £24
Mickey