Can I rent a car from Redding, CA and turn it in at the Oakland Airport? And if so, is there an additional charge for not returning the car to the original rental city?

you have to negotiate with them. they may need to get a car returned.

Thanks for the replies, I'll do more checking.

I picked up a car at the Oakland airport and dropped it off in downtown San Francisco without paying any extra charges !

You'll have to pay a fee to drop off different location u can find the fees when u check out there website

Yes you can. Only went you rent it, they ask were you want a return the vehicle and you need be specific. Or call customer Service, they can help you.