My commercial lease (CA) has an auto renewal every 5 years, new owner wants me out. Is this legal?

You are screwed.....according to CA law. The fact that you have been there for years and want to stay is 100% legally irrelevant. There is no law that forces a landlord to continue to rent to a tenant as long as the tenant wants to stay there. I would hire a lawyer and have THEM give you their two cents about the contract