RE: Oil spatter
Seems that everyone here is trying to make out like the engine has a problem or that any oil on an airplane signals a problem. Maybe not the case at all!
For example, I run 32:1 in all my engines. My choice and like so many others I've used Stihl HP Ultra over the last two seasons. Most of my airplanes have very little to almost no residue on them but one, a 30 sized YAK is always a mess after a day at the field. The only difference compared to the other airplanes ..... a different muffler that has the stacks shortened so the cowl can go on and off easily. The stacks simply don't get the exhaust far enough away from the plane so any residue gets deposited on the bottom of the plane. No great problem as one pass with a rag and its gone. So that means there is an exhaust problem, not an engine problem, not an oil problem, not a DA vs the world problem, not a 32:1 vs 100:1 problem and not even a synthetic vs dino oil problem. In fact, not a problem at all.
Good god all mighty, these are engines that are burning fuel that has oil mixed with it. Not all of the oil burns so it has to go somewhere. In fact, some synthetics hardly burn at all in the combustion process so a great quantity is discharged with the exhaust ... so where does it go? In some cases, on the bottom of the airplane.