I see the JD multi-purpose lithium is suggested in the manual. I've typically always used these packs of 3-oz. cartridges available at most hardware stores, etc. paying absolutely no attention to what brand they are. I always have to wonder when a manufacturer recommends using only their brand-name products - in this case the oil, transaxle fluid, and so forth - as to how critical it really is. I have 10w-30 for the 590 (hasn't used any yet since I have it) - but it's not JD. Think it's Wolf brand.