my oil sump is leaking

Yes you can do it yourself. First you must see if the oil pan will come out once you have unbolted it. If not look if the engine will need to be lifted off of its motor mounts, once the oil pan is removed scrape the gasket surface clean and then install the new gasket while using sealer, let the sealer dry then recheck the tightness of the bolts and then reassembly the remainder of the job. Let the sealer dry for a day before installing the new engine oil and you are all set.

Please let us know happens so it will help others.

Best, Ken