If you are not afraid of the epa, used motor oil works well at preserving wood (just don't sit on it!). Ideally, you would dilute the oil with a little diesel fuel in a shallow pan and set your wood in it, end grain down, and let it wick up the wood.after a day or so, turn the log over. After a few days your wood will be fairly well protected. The volotiles will evaporate in a few days and should not easily catch fire from sparks or the occasional hot steel. :d