Ask an expert

I am not sure what type of oil was used when my car was serviced a few months ago.

Does it matter what type of engine oil I use for topping it up? Are the various mineral oils (and their additives) that are sold for car engines compatible e.g. does it matter if I mix 20W-50 of one make with 10W-40 of another make?

If you are sure a mineral oil was used, it isn't critical which oil you use for top-ups, they will all mix together OK.as long as it is mineral oil. Obviously, if you know what oil was used, it would be preferable to use the same grade.