Differentials and transfer case oil/fluid change intervalls: '99 1500 Z71 5.3l

[czissman]

The factory service manual doesn't address the topic of oil change intervals in the differentials or fluid change intervals in the transfer case. Does Chevy not call for this to be done at all? Seems odd to me. What say you on these intervals?

[dsr611]

From the Hayne's manual

https://haynes.com/en-us/tips-tutorials/1999-2007-chevy-silveradogmc-sierra-pickup-truck-and-related-suv-routine-maintenance

 

Every 60,000 miles or 48 months, whichever comes first

• Change the manual transmission lubricant**
• Change the transfer case lubricant**
• Inspect the Exhaust Gas Recirculation (EGR) valve
• Change the differential lubricant**
• Replace the Positive Crankcase Ventilation (PCV) valve

 

** If operated under one or more of the following conditions, perform these procedures at half the recommended interval

• In heavy city traffic where the outside temperature is regularly above 90-degrees F (32-degrees C)
• In hilly or mountainous terrain 
• Frequent trailer towing 
• Frequent off road use or if the vehicle is driven through water

Edited May 13, 2023 by dsr611

[czissman]

Thanks @dsr611!