Add Transmission Fluid: 2025 GMC Sierra 2500 HD AT4X 6.6L V8

This video shows you how to add transmission fluid to your 2025 GMC Sierra 2500 HD. Before contemplating a transmission fluid change and searching for the transmission fluid change cost on a Sierra 2500 HD, see if you need to add transmission fluid. How to add transmission fluid? First, make sure that your engine was running when you checked the fluid level. If the transmission fluid level on your Sierra 2500 HD is low, you need to add fluid through the dipstick tube or the check plug. GMC has developed sophisticated transmissions through the years and it is critical that you add the exact type of transmission fluid stipulated by your owner's manual (typically in the back of the manual in a section titled Fluid Capacities.) The manual will likely call for a specific type of GMC transmission fluid. It may state a type such as Dexron, Mercon, Allison, Type-F or CVT transmission fluid. If you are going to use a different brand of fluid such as Valvoline transmission fluid, be sure it matches the type specified in the owners manual. When adding transmission fluid to your Sierra 2500 HD, be sure to add it slowly as the transmission fluid capacity is reached quickly and it can be difficult to remove excess fluid if you overfill.

When to add transmission fluid to a Sierra 2500 HD? If you are having problems with the transmission in your Sierra 2500 HD, such as clunky shifting or hesitation, check the transmission fluid level first - it is amazing how many drivers pay thousands of dollars for transmission work when a half quart of transmission fluid would have fixed the problem.