Depending on how you propose to handle the saw in the future, or not handle it, it matters where and how it is stored. WD40 evaporates rather faster than most people realise so you would need to keep a close eye on the saw as time passes in order to re-coat it. Alternatively you could, after applying WD40, wipe ordinary engine oil onto it - make certain it is clean and unused so as not to risk sulphur compounds in too great a concentration. This sort of treatment should preserve the saw's finish for months at a time.