I never had a problem with Pep boys taking a mix. The oil goes to a recycling center where it is separated and taken care of the correct way. Well that is what the service writer dude told me when I left several gallons of head gasket milky oil /coolant a while back. They only take up to 5 gallons a visit I was told last time I made a deposit
think I have 5+ gallons waiting to be recycled myself in the garage now.
I am just passing on info I was told so if I am incorrect please correct me on this.