First off, I'm a brand new airplane owner, 10 weeks now, 6 of those weeks my 62 M20C was down for a broken tach cable. I have a similar leak somewhere in my IO-360-A1D. The only mechanic on the field looked at it twice already and keeps telling me its venting out of the breather tube. I don't know exactly where I need to fill it up to before it wont blow out yet, but I've heard that if you fill it to 8 quarts you will dump at least two of them. I have tried 6 quarts, lost a quart on a three hour flight, tried starting at five quarts, lost about a half quart on a 2 hour flight. Then, to make things worse, the only mechanic on the field has moved out of state. Now I need to find another mechanic, hopefully he knows more about Mooney's and find this leak. I don't think its venting out a whole quart out of the breather tube, or am I wrong?