Re: Olive oil to prevent burr comb
The bees will clean up the olive oil and if they are going to build burr comb, they will still build it.
Also, as per Jeanette, olive oil is probably not the greatest thing to put in a beehive.
Your burr comb can be better handled by the way you set up the hive. First off, all hives have burr comb you need to get used to it, if there is a suitable gap the bees will fill it. However hives using combs built on comb foundation and having less than the natural amount of drone comb, build a lot more burr comb as they'll squeeze some drone cells in anywhere they can. If you allow your bees to have a comb or two of drone comb they will build a lot less burr comb. To let them have a frame of drone comb just put in an empty frame, no foundation. They will fill it with drone comb.
44 years, been commercial, outfits up to 4000 hives, now 120 hives and 200 nucs as a hobby, selling bees. T (mostly).