Given the way an aircraft engine is run, it has a pretty long interval between overhauls.
Plug fouling in normal operation is not usually a problem. To ensure that all cylinders will likely fire, aircraft engines have dual ignition (top and bottom plugs in each cylinder), by magneto, which is entirely independent of the airplane's electrical system.
Try running your car wide open all of the time, and see hown long the engine lasts. This is permissable with most normally aspirated piston aircraft engines. For that matter, with rare exceptions, 75% of rated power can be used continuously, for as long as you have fuel. I don't think any car engine can do that.
There was once upon a time an M1 aviation oil. In the right engine, it produced exceptionally low wear. In the wrong engine (mainly the old 90 octane engines, a fuel no longer available, so one must use 100LL), its poor lead scavenging caused problems, and failures.
M1 Av was withdrawn from the market.
AFAIK, there is no pure synthetic approved oil for type certified piston aircraft at the moment.
Incidentally, drain intervals are typically 50 hours for engines without oil filters, and 100 hours for those that have them.
This means that in a fast single, the oil is run the equivalent of 10K miles+, allowing for taxi, climb, descent, etc.
Oil additions will be required, and the sump capacity is generous.
