Hi, Marci! You're welcome.
I'd bet it would work just fine with olive oil, I've seen other recipes that used it by itself. Here's another one I found that's very similar but only uses one kind of oil:
Mayonnaise
Yield 1 ½ cups
1 large egg
3 Tbsp. cider vinegar
½ tsp. salt
½ tsp. dry mustard
1 ¼ C. oil (vegetable, olive, and/or canola)
Blend the egg, vinegar, spices, and 2 Tbsp. of oil for a few seconds. Without turning off the blender or food processor, slowly pour in the remaining oil. As soon as it is mixed in, turn of the blender and transfer the mayonnaise in the container.
Laurie*