The cake recipe is calling for a vegetable oil. I have refined sunflower oil, and refined soyabean oil.
Do they qualify for flavourless oils? I haven't noticed any taste in any oil by now! Taste buds problem, perhaps.
Both refined sunflower oil and refined soybean oil are generally considered flavorless.
Also included among these are:
The most reliable method of course is to taste the oil :). I'm sure you can actually taste the flavor of extra virgin olive oil.
Most refined oils have little to no discernible flavour. It's the unrefined oils (think EVOO or dark sesame oil) that do.
I wouldn't hesitate to use refined sunflower oil or soybean oil in a cake; nor canola, peanut, grapeseed, or safflower. They're all pretty bland.
Really, the best way to know for sure is to taste it.