The oil is lube for the gears most blowers leak enough that changing the oil isn't a thing to worry about. I use a mix of Marvel mystery Oil and 30 wt non detergent oil. Ask six smith's what's right and you will get ten different answers. LOL If the smaller one is a Bufco sheet metal blower like the one I have it was not meant to hold oil I lube mine with white grease.
Finnr