Theoretically any retailer in California that sells motor oil is supposed to collect it regardless of where it's from, or at least that used to be the case. Mostly this means auto parts stores or auto repair shops, but theoretically it includes places that barely sell oil like supermarkets or convenience stores. Maybe even self-serve gas stations. There are lists of certified oil collection places. We have a fee on new motor oil that goes to paying for some of the costs of used oil collection.
I typically take it to one nearby city's recycling center. They usually have at least one 55 gallon drum with capacity, although occasionally one overflows before an employee seals it and puts another one in service. It works a bit better than their previous setup, which was a single used oil tank that would sometimes overflow and had to be taken out of service. This place is pretty convenient too, since they have collection of old fluorescent bulbs, all sorts of batteries, etc. They also take cans, bottles, paper, although they don't pay for any of that. Maybe 30 years ago they did. I distinctly remember they paid for used motor oil. I do think they get paid for the recycled materials, but for the most part people just want to get rid of it.
Another option is one of my county's hazardous waste collection facilities. I think they might be able to take up to 15 gallons of motor oil at a time from a private resident for free. They charge businesses though. They also take a lot of hazardous wastes. I've dumped off used coolant as well as my oil soaked paper towels and drop cloth that I use during oil changes. They'll take lots of things, including stale fuel, pesticides, and even asbestos. I remember the last time I tried it I was greeted by a county worker wearing a Tyvek hazmat suit. Before they opened my local facility, the county only had a single facility. They would (and occasionally still do) have hazardous waste pickup events in a large business's parking lot. I made an appointment once to get rid of some coolant. I also had an unopened case of motor oil in my trunk, and they joked if I wanted them to take that.