The engine is installed in a Sonex taildragger. I fitted some large diameter wheels to go bush, but did not recalibrate the dipstick to allow for the increased nose-up angle. A combination of false dips, complacency on my part - because until then it had used bugger-all oil - and siphoning out through the oil filler into the collector bottle then overboard, nearly got me on a very long day's flying where I did 9 hours. Early in the day I put half a litre in, not realising that the other half went overboard as I taxied out. A whole lot more probably dumped during the next 3 takeoffs, so several hours later it got rather interesting. What I do know is if the oil temperature starts to decrease on a hot day, you are about to run out of oil, so that was my first clue. I promise to dip oil before EVERY flight from now on.