can you use extra light olive oil in place of vegetable oil with cake mix?
No! It will taste terrible! I've done it, once!
Yes, you can use extra light olive oil in place of vegetable oil with cake mix but there will be a slight difference in taste because of the filtering. The link below has additional details on how it can be done http://www.ehow.com/how_5733353_use-place-vegetable-oil-recipes.html.
The taste will be different. Oils like Canola and vegetable oil have almost no taste while olive oil has a more pronounced flavor.