I didn't know that people still used yoyo's or would admit to doing so.
...or that yoyo's had bearings.
...or that someone would actually take the time to lube their yoyo bearing.

Anyway, most bearings would fair better with grease but I think the manual says to use a lightweight oil.
If so, you should be fine as long as it's safe for plastics.
I can't imagine what yoyo's are made of these days.