Just bought a 99 c280 with 59 000 km on it .. acording to the records the oil was changed at 54 000km and 5w40 quacker state synthetic was used. The dealer bought the car with 58 000km at an auction he does not know if his mechanic changed the oil or what type of oil his mechanic used if he changed it at all.

I want to continue using the 5w40 QS synthetic do I need to get the engine flushed? is there a way I could tell if the oil is synthetic or regular.

It's posible that the dealers mechanic used regular oil if i put synthetic in it without flushing the engine is that going to be a problem??

thanks