For years I used any random 5W-30 in an old school, metal pump style oil can, then decided that was too much of a pain to hit every tooth, nook, and crannies individually, so now 0W-20 in a trigger pump style sprayer bottle. It is important to do as mrsilv04 wrote, to spray excess, run it a moment, let excess drip off and wipe it. That will not only lube but also work some grime out.
I never noticed any significant problem with leaves not liking the motor oil but you could use mineral oil if you wanted to.
WD-40 or gasoline would be better to flush it all out at end of season before lubing it again for storage, unless it's due to have the blade assembly taken apart (if that's also how you sharpen instead of put together, can depend on tooth density which is easier) and cleaned while apart, unless it's one of those electric disposables where the blades are riveted together.