Mobil Corp. is taking several cost-cutting steps.

Bracing itself against expected lower earnings if oil prices stay down, the oil company ordered a hiring freeze and a three-month delay in pay raises, Chairman and Chief Executive Allen E. Murray said. The company had earlier announced a reduction in its planned 1986 new capital spending and exploration program by $1.1 billion--or 27%--down to about $3 billion. In a separate development, Standard & Poor’s said it was lowering the firm’s Mobil Oil Corp. subsidiary’s credit rating on $6 billion of senior debt to AA- from AA because of the impact of lower petroleum prices on the company’s earnings.