Hopefully i can help..
Normally on these as a common fail in regards ***** ***** leaks is due to the rocker cover gasket..sometimes this causes oil smell into the cabin..when they come to replace that they have to remove the coils anyway to that /what about checking the sparkplugs but the tube in which the sparks sit or even take them out should be checked for oil as any oil forming around the sparkplug and the end of the ignition coils can cause the voltage from the coil to arc and thus damage the coil/cause a missfiring fault - the tube in the cylinder head they have o ring top and bottom..if the coils ends or the sprakplugs are drowned in oil then that the problem..normally seeing as you have the EML on at the moment is to get the faults retrived,the car scanned and see if the fault codes relate to the coils or some other fault....
As far as your airbag warning goes..your dealer is wrong saying its nothing - they should know by now that recently airbags/srs faults or warning lights constantly on are a fail item as per MOT ..so it has to be to rectifed or the airbag light should go out at each time the car is used/engine started once the airbag ecu has self tested - if not then car will fail mot
Thanks for the help that made a lot of sense now when I go back to the garage I have gained some knowledge and want be satisfied until they excapt their responsibility.
Thats fine..glad to help..But should you need to ask anything further or need advice etc..then just continue on this same post if required..
Anyway hope you get things sorted out all the same...