...and here's the information you need to understand how & why: http://curezone.com/blogs/fm.asp?i=985358
"Technically" the safflower oil should be as effective as olive oil. But the 'science' doesn't explain why virtually every healer (and Cayce) has consistently used olive oil for liver health & flushing...especially when decades ago, olive oil wasn't easy for many people to find/buy. I certainly understand about the 'taste factor' as I love olive oil and I'd read of many people that developed an aversion to it after flushing. That's one of the reasons why I started adding a tablespoon or two of ginger root juice to my oil...not only does it increase the flow of bile and help prevent nausea, it covers up the taste of the olive oil quite nicely.
Be sure to use organic, cold-pressed; it's REALLY important that the not be "processed" (personally, I'd go with the olive oil...I can't stand the idea of "wasting a flush"), but if you choose safflower, be sure it's cold-pressed. Of course, they're your flushes, not mine - if you feel comfortable that the flushes with safflower oil are effective, (and going with a different oil vs using the one healers have utilized consistently), it's always up to you.