Lubrication - Service Intervals

Check fluid level whenever performing other underhood services. Draining, refilling and band adjustments are not required under normal driving conditions. Under heavy duty (severe service) conditions, change fluid, replace filter, and adjust bands (if applicable) every 15,000 miles. On ZF 4HP-18 units, the transaxle fluid and filter screen should be changed every 30,000 miles but, while the differential must be checked, the fluid need not be replaced.