We have a similar problem with an 0-200 with 400 hours since TBO and the engine it replaced did the same. It doesn't seem to affect starting or mag drop. I am not an engineer and there are a couple of issues over the behaviour of oil that puzzle me. The second one is that, when we check the oil level when the engine has been standing for a day or so, the level on the dip stick is always a good half inch above the limit. When you wipe the dipstick and recheck, the indicated level is normal. This suggests to me that, as the engine cools, the oil draining back into the sump gathers into odd places such as No 4 cylinder head and the dipstick tube. We have found that, if we stop the engine at the end of the day by slowly winding the mixture back, we get less problems with oil in No 4.