Sorry, in your 2nd Ask you did say which engine it has. This is a tiny engine working very hard. I suspect that oil is getting past the turbo oil seals into the combustion chambers. Though the turbo is water-cooled, you should still be aware that it gets very hot and to help the turbo cool down properly should should idle the engine for 30 seconds before switching off whenever it is fairly hot (such as after ascending a hill or when stopping for petrol on a motorway or after thrashing the car cross-country).