Limes are fine.
You can try all of the following:
lime, lemon, any soda like cocoa cola, ginger ale, sprite variants, or add some Sugar
Coca cola helps to get more oil down. See Doc Sutter for info on coca cola flush, not that there is anything more than just adding oil to it.
Note that there is large scale fraud in the olive oil industry. Many olive oils are really rapeseed mixed with other nasty oils. Some extra virgin oils are actually just pomace oil (the lowed quality olive oil - tastes like motor oil)
The best oils imo come in metal tins from greece, italy, spain, tunisia, etc. Though not all bottled oils are bad.
And as long as I'm ranting, there is also fraud in the flax seed oil industry as well, or my taste buds have improved a lot. I used to take Barlean's oil regularly but now it tastes distinctly rancid to me.
In fact if you want to be a hero, get an oil pressing machine (google), and make your own oils.
I drink a lot of rice milk and the only brands that taste good to me are ones that use organic cold pressed oil.