Reduce the amount of bittering hops you use by about 25% when doing full boils. Also, take extra care with aeration, you will no longer be topping off with fresh oxygen rich water.
I've used olive oil for 6 full boil batches now. 1 drop is sufficient for a 5 gallon batch. I do full boils with absolutely no aeration and the beer ferments out to the desired gravity in a reasonable amount of time with no off flavors. This is all :off: sorry.
Just an FYI. A wort chiller is not absolutely needed for full boils. I do full boils without one, I just use an ice bath and I can easily get down to 75 within 20 minutes. Another issue to consider with full boils is aeration. A full boil removes basically all the oxygen from the wort as...