Cal. Pub. Cont. Code § 10408

(a) Every procuring agency shall establish and maintain an affirmative program for procuring oils containing the maximum content of recycled oil.
(b) An affirmative program shall include, but not be limited to, all of the following:
1. (1) The placement of descriptions of the preference for recycled oil products in publications used to solicit bids from suppliers.
2. (2) Description of the recycled oil procurement program at bidders’ conferences.
3. (3) Discussion of the preference program in lubricating oil and industrial oil procurement solicitations or invitations to bid.
4. (4) Efforts to inform industry trade associations about the preference program.