Generally a fully synthetic will be able to cope with longer service intervals compared to a semi. Its down to the user and his purse but why not put the best stuff in. Oil is cheaper than a new engine.
Tho it would be a waste to throw out fully synthetic after 4 or 5k miles use.
Maybe I didn't word my question correctly.The car is only a couple of weeks old, and I wondered what type of oil was in it from the factory. I wouldn't want to top up with the wrong type of oil. (not that it needs it at this time) It's just to make sure that I know. Since I have a litre of fully synthetic un-opened. Although I shouldn't really need to top up between services, unless it sprouts an oil leak.
My understanding was diesels prefured fully synthetic all the time anyway due to longer servise intervals than petrol engines cars.? Is magnatec endorsed by Kia? I know it may affect your warranty to put in another kind of oil.