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, change transaxle fluid and filter screen every 30,000 miles. Although differential fluid level must be checked, fluid need not be replaced. On F4A22, F4A33 and W4A33 units, change transaxle fluid and filter screen every 30,000 miles.