I have a new 2010 GMC Savana and it will be needing its first oil change soon. I am going to get synthetic oil, They have Mobil 1 at the dealership . Right now they have a $19.99 deal for an oil change with regular oil. I called up and they said it would be $23.99 extra for Mobil 1 Synthetic. What do you pay? at your dealership or elsewhere? Is $23.99 extra about what one would spend for synthetic instead of regular oil? I called another GMC dealership and they said $90 I am not doing it myself so don't bother suggesting it.