mate the v6 ecotec needs a more thick oil as they are pushing now more then 10 years now. 10w30 or 10w40 is bullshit u need at least 15w40 or 20w50. at first when holden recommened 10w30 for ecotec engine that was 10 years ago on a bloody new engine lolllllllll.
using a 10w30 in an exotec more then 10 years old is really a joke. in the owners manual they recommend 10w30, but that was more then 10 years ago guys come on wake up guyssssssss.the correct oil grade for any car is by how much km on the car and by how old it is.