Hi John the oil explains the high hydrocarbons with a lot of oil floating around more than likely explains the good compressions,but it may have knackered bores & oil rings burning oil will also push up the C.O. Whats the mileage? has it been clocked? is it still the original engine? does it have blocked breathers? out of interest what spark plugs are in it at the moment? is the O2 sensor switching niceley should be somewhere between .03-.60Mv. have you scoped it? John Kennard.