TM 10-3930-653 14&P Organizational Preventive Maintenance Check and Services A-Annually H-Hours Item Interval Item To Be Inspected No. A H Procedure:  Check For And Repair, Fill Or Adjust As Necessary. 13. HYDRAULIC SYSTEM NOTE When checking oil level, insure that engine is shut down, forks are on the ground or floor and that the truck is on a level surface. 1200 a. Replace hydraulic oil return filter. 1200 b. Clean hydraulic oil suction filter.  Check condition of oil suction filter gasket. 1200 c. Drain and refill to bring oil level between the two slots:  high and low. 14. RADIATOR • Check coolant for antifreeze and corrosion protection and inspect tool- ing system for heavily rusted or partially clogged cooling system (ref. TB 750-651). B-42