oil on my spark plug cable

Today i look at my spark plug cable and it had oil. The car is riding the same.Is it serious and how much will it cost me.

you mean plug wire? if it was just oil on the outside you probably just have a leak somewhere may want to clean your engine and run it and just watch if you dont see anything leaking bad then drive it for a day and you should be able to find your leak

Depends where the oil was located. If it was on the boot that slips over the spark plug then your spark plug tube seals are leaking. They are very simple to replace. All you do is remove the valve cover and remove the old ones from around the tube and replace them with new ones along with a new valve cover gasket. It is really a very simple project.:)