Chainsaw Bar Oil Question

I have what might be a stupid question but here goes.
Bar oil, is there anything special about it?
I went into a hardware store today to pick up some bar oil, they wanted $24.00 for a 2qt jug.I
I'm thinking the bar oil I've ever used was nothing more than maybe 30 or 40 weight oil.
Possibly detergent oil?
Can I just use motor oil?
I need a chainsaw maybe 2 or 3 times a year. I'm not making a living with a chainsaw, but $24 for 2 qt.s was steep.