Don't use WD-40 except as a cleaner. It is too thin and will simply wash away any oil that is already there.

Don't use vegi oils. They not only turn rancid quickly but also get gummy and will hold onto every speck of road grit and shorten chain life.

Motor oil would work well. Use plenty of it, then plenty of paper towels to remove as much from the outside of the chain as possible.