Diesel fuel is $4 a gallon here. My used motor oil is FREE. Everybody got that?
Early morning, lots of dew, no wind also works well.
I much agree with the dew comment. We prefer starting brush piles at dusk when the dew point is high and the wind is low. If any embers were to drift away they're easy to spot in the darkness. Another safe idea to keep fire from spreading, we allow the fire to burn away from the pile about 6-10 feet to remove any fuel (grass).