Re: Excessive oil use
Need more information...I assume you are using VRO??
If so, at 50:1 you should be burning roughly 3 pints of oil (70 liters = ~18.5 gallons), assuming one pint every six gallons and premix. I assume you should be using even less with the VRO metering less oil at idle. So you are getting an additional 5 pints mixed in that same volume of gas. Further than that I cannot help you...probably a VRO pump issue, but as long as your pump is working as it should, your plumbing is clean and leak free, and you're getting good crankcase pressure to the VRO pump it should be working fine. My guess would be bad VRO pump.
Have you inspected the plugs and looked inside the cylinders to check for fouling?