Gear Oil

Regular old mineral based GL-5 with LSD additive already in it is available at some places. Valvoline used to be widely available, but stopped putting in the additive a few years ago. Castrol is out there, Amalie, and Walmart brand Super-tech. It's nothing fancy, brand should make little difference. Or like Rusty said put the additive in yourself, only enough to get it to stop chattering.