If I was you, I would do an oil and filter change. Can easily be done for around £15 for both oil and filter.... or you could get expensive oil and the price can be alot higher.... As long as you do your oil and filter change regularly then cheap oil isnt really an issue.
so.... drain your oil..... replace the sender, put new oil filter on and the Sump nut. (new sump nut and washer is ideal) Then fill it up to the correct level.
Hopefully.... Leakless oil and clean oil, meaning good for your engine

Hope this helps