Thanks for the thoughtful replies.
Her Yaris does have the 1.5L engine with VVti, not sure of the Toyota engine designation yet.
The manual specifies a 5W-30. So, pretty much the consensus is to go with either a) Mobil-1 5W-30 HM, b) something like SuperTech 5W-30, or c) a non-syn 5W-30.
Pretty much I am hearing to stay with the 5W-30 grade...Sound about right?