Mich. Comp. Laws § 125.555

Sec. 5. Fuel oil or any other oil or liquid used for equipment installed under this act shall have a flash point of not less than 100 degrees Fahrenheit as determined by an appropriate closed cup tester method specified in the American standards of testing materials standard for fuel oil. In determining the flash point of oil, a tester as required by the department of buildings and safety engineering shall be authoritative. Fuel oil shall not be mixed or blended except at a storage plant under competent supervision, and waste oil shall not be used except with the approval of the bureau of safety engineering.